It is back-to-basics time for the women's movement.

Rebuffed in their efforts to gain an appreciable number of appointments in the Reagan administration and increasingly resigned to the imminent failure of the ratification drive for the Equal Rights Amendment, the political feminists would seem to have fallen on bad times.

But if this is a time for gloom and doom, someone forgot to tell Kathy Wilson, the new head of the National Women's Political Caucus.

"My main goal," the 30-year-old Wilson said the other day, "is to get the women's movement off the defensive, and the best way to do that is to get back to our original purpose--increasing the number of women in political office."

To that end, the steering committee of NWPC spent this weekend in Washington putting the final touches on what it calls a "Win With Women Campaign," designed to recruit, train, finance and elect more women to public office--particularly in the state legislatures.

The choice is eminently practical. The legislatures have been the biggest breakthrough area for women in politics. In the decade that the NWPC has been in existence, the number of women state legislators has increased from 362 to 901--from 5 percent to 12 percent of the total.

This year's redistricting in almost every state will open new districts-- and new opportunities. State legislatures are becoming more important arenas of policy-setting, particularly for human-service programs, as President Reagan pursues his long-range design of transferring responsibility for those programs from Washington to the states.

And state legislative posts are important political steppingstones. As Wilson noted, more than 60 percent of the women now in Congress served previously in their state legislatures.

Given all these facts, the decision to concentrate on electing women to the legislatures seems obvious. But, in fact, it represents a change of direction.

For the last several years, as the ERA proponents fought for ratification against increasingly stubborn political resistance, much of the energy of the women's movement went into the task of electing supporters of ERA and defeating its opponents. Inevitably, most of those contests involved districts where the candidates were males.

While Wilson does not put it quite so bluntly, the fact is that feminists got so involved in electing or defeating men, based on their position on ERA, that they neglected the fundamental task of getting more women elected to positions where they could vote on a range of important issues.

The essentiality of having women in elected office has been reinforced, not just by the loss on the ERA issue, but by the stinginess of the Reagan administration with female appointments.

Last week, Wilson, a Missouri Republican now living in Virginia with her husband and young daughter, noted that despite Reagan's claim to have named more women appointees than any of his predecessors, he is in fact lagging far behind Jimmy Carter. Further, she said, "the positions which these individuals hold are clearly less powerful than the positions held by women in previous administrations."

But instead of sulking about their treatment, Wilson and her colleagues have dug in their heels for a fight in the precincts this year. The materials they have prepared for their drive to elect more women legislators show a thoroughly professional approach to recruitment, organization, fund-raising, publicity and campaigning.

But, as Ruth B. Mandel, the director of the Center for American Women and Politics at the Eagleton Institute of Rutgers University, has noted, women candidates still face tough odds in the competition for cash, for workers and for votes.

The NWPC is not a juggernaut. While it has chapters in all but four states, its active membership is just over 10,000. It has had its internal splits on endorsements, with a good deal of disaffection in 1980 by Republican women who saw it as an automatic ally of the Democrats.

But Wilson says 35 percent of the membership is still Republican, and she has begun to use her own Republican credentials to heal the breach that developed in 1980. NWPC now seems pointed on a path that will help, over the next decade, bring many more women into elective office at all levels and in both parties.

To anyone who knows the quality of the women who have pioneered that path in the past decade, that is cause for rejoicing.