In federal-state relations, money talks.

When Washington tells states to jump, and money is involved, they usually obey. But orders by Congress and federal agencies to take certain action or face cutoffs in federal funds often are regarded as interference with states' rights and tantamount to blackmail.

Washington prefers to view the commands as justifiable pressure for the common good. Whatever it is, there is no denying that Washington generally gets the results it wants.

''The threats are effective, all right; there haven't been that many penalities imposed,'' says Bill Blessing of the policy planning division of the Federal Highway Administration, an agency that dispenses roughly $10 billion to the states in road and highway help.

He notes that all 50 states, in accord with Congress's legal wishes, set maximum speed limits of no more than 55 miles an hour and thus earned federal funds that might otherwise have been denied. And he says that although some money was originally withheld from states that did not comply with Interstate Highway billboard regulations, all but one state eventually made the required changes and got the funding restored.

Whether the issue is education or the environment, safety or civil rights, states usually want the money enough to comply.

''You usually dance to the tune of whoever is pulling the purse strings,'' says Miles Ferry, president of the National Conference of State Legislatures (NCSL).

In the case of federal funds linked to school desegregation progress, however , there was a time in the 1960s when hundreds of school districts lost their share of Washington funds. But because a constitutional issue of civil rights was involved, Washington had a powerful backup weapon - the court order - that usually did work.

''For political reasons some school boards waited so they could say, 'The government made us do it,' '' recalls one veteran Washington bureaucrat closely involved in a number of such cases. Fund cutoffs, he adds, tended to be politically tough to administer, particularly in education because disadvantaged youngsters were hardest hit by the cuts.

But the question of Washington's authority to lay down the law in such varied realms is a thin-ice issue in the eyes of many state legislators and governors. Some argue that Washington has already far overstepped its legitimate boundaries.

Particularly nettling to many at the state level is the new law withholding up to 10 percent of highway construction funds from any state failing to raise the minimum drinking age to 21.

Washington's move, says National Governors' Association spokesman Bernie Chabel, tends to ignore the many intensive state efforts long under way to stiffen drunk-driving penalties.

''It's the heavy hand of the federal government taking what it can get in an emotional effort,'' Mr. Chabel says. ''The issue is really the driving and not the drinking age. But the federal government would never establish a nationwide driving age. The public would be much more inclined to see that as a state and local preserve.''

At the heart of state objections is resentment at being told, in effect, that Washington knows better.

''We feel we're equal partners in the federal system,'' explains Mr. Ferry, who is president of the Utah Senate. ''Most state legislators are fairly independent.'' He notes that a few states which passed 55-mile-an-hour speed limit laws, in effect added their own stamp by making the penalties very light or nonexistent for drivers caught going slightly faster.

Ferry strongly favors a system of monetary rewards rather than penalties for states that follow Washington's bidding. ''Legislators would far rather have a carrot than a stick,'' he says.

And he applauds Congress's recent decision to increase highway safety funds for any states passing laws requiring mandatory sentences for drunk drivers.

Cracking of the federal financial whip is a more appropriate weapon, most state leaders argue, in the realm of auditing the use of US funds. If money is misspent, Washington can and often does order it paid back. Even so, states often push hard in such cases for deadline extensions, as they do with more traditional funding threats.

The NCSL, spokeswoman Sharon Brown says, has been pressing federal authorities to hold back on their plans to mail out fiscal sanction notices to states that have higher than acceptable levels of error in Aid to Families With Dependent Children payments. ''We think the method of determining sanctions in some instances is unfair and does not take into account state efforts and progress in improving those error rates,'' she says.

Whatever the proper mix of federal vs. state power, experts say the balance is not as one-sided as it appears to many state legislators. They say the federal funds threat, for instance, is likely to be effective only if there is already substantial support - in state action or public opinion - for the idea in question.

''My judgment is that this kind of thing does hurry history along, but you don't dare use the threat unless it's an idea that has pretty wide support,'' confirms John Shannon, assistant director of the Advisory Commission on Intergovernmental Relations.

NCSL president Ferry says he thinks the situation has eased somewhat during the Reagan administration's tenure: ''He's more of a champion of states' rights, and there hasn't been quite as much enforcement of some of these mandates.''