WASHINGTON (AP) _ Reclining regally in a corner chair in Elizabeth Moynihan's dining room is a lifesize papier-mache likeness of a 500-year-old emperor who must surely seem like one of the family by now.

With his turban, royal robes and unflappable grin, the Indian ruler Babur seems at home in the household of a couple who has trekked about the globe and weathered Washington from the White House to Capitol Hill.

Liz Moynihan, an exuberant woman with a halo of white hair, is married to Daniel Patrick Moynihan, the senior senator from New York, but she fits no one's stereotype of a traditional Senate wife.

''I don't make the scene here. I don't have time to. I'm not interested,'' she says.

Mrs. Moynihan, 55, avoids the cocktail circuit, official receptions and press interviews. What she is enthusiastic about is Babur, a descendant of Ghengis Khan and the founder of the mighty Mogul dynasty of India in the 16th Century.

The Moguls built some of the world's most important monuments, including the Taj Mahal. Babur's lotus garden near Dholpur is believed to be the earliest Mogul site in India.

Following clues in Babur's autobiography, Mrs. Moynihan drove around for five days and then tramped through dirt, straw and cow manure to find the garden during a 1978 expedition. She found a stone platform and a lotus pool.

''It's all covered with cow dung, but there it was, so I started yelling and clapping,'' she recalled.

Startled villagers, some of whom had never seen a western woman, came running out of their huts and ''thought this was the funniest thing they had ever seen,'' she recalled.

''It probably was,'' she added.

Mrs. Moynihan returned to India to celebrate Babur's 500th birthday two years ago and again last winter on a grant from the American Institute of Indian Studies to document the garden. Her trips have rarely been underwritten.

''I've never been able to get grants to do anything. I've tried and just haven't had any luck,'' she said. ''If your husband's a senator, it doesn't open doors for you. It limits the possibilities, I find.''

Mrs. Moynihan has written a book, ''Paradise as a Garden,'' about pleasure gardens in Persia and Mogul India. She would like to do more extensive work in the field, but there is only so much time.

''It's hard for me to be away longer than, say, six weeks,'' she says. ''It's not like we had a big staff who was going to change the lightbulbs or call the plumber or get the dishwasher fixed or something like that.''

The Moynihans live in a gray townhouse with a modest yard and black wrought-iron fence in the Capitol Hill neighborhood, a few blocks' walk from Moynihan's office in the august Russell building.

To get to the kitchen, guests pass through the dining room and beside the imposing figure of Babur, created by Mrs. Moynihan's son Tim. (They have two other children, Maura and John.) On the sideboard are drawings of the emperor's lotus garden.

But Mrs. Moynihan is not totally wrapped up in her Indian studies.

''I do all Pat's politics,'' she says. ''We're trying to raise money this year for Pat's '88 (campaign). If you don't raise it this year, next year you can't because of all the '86 candidates. It's just going to cost so much that you have to raise it this year. That's what this is all about.''

Her political acumen is obviously honed from years of public life. The Moynihans met while working on Averell Harriman's campaign for governor in the 1950s.

Her husband, a Democrat, has had a distinguished career marked by an ability to work with presidents of either party.

His work in the Kennedy and Johnson administrations resulted in landmark anti-poverty programs. He was a White House counselor to President Nixon, and in 1973 became ambassador to India. In 1975 he became U.S. ambassador to the United Nations under President Ford. He also has taught urban studies and government at Harvard and the Massachusetts Institute of Technology.

It was while they were India that Mrs. Moynihan discovered that the whirl of the diplomatic life was not for her.

India was at first ''a terrible culture shock,'' she said. She reacted by developing and pursuing her interests in the land, its culture and archeological history. She often took train trips with friends to explore.

Her consuming project now is a treatise on the lotus garden. She believes that the use of the lotus, a traditionally Hindu symbol, in a garden commissioned by Babur, a Muslim, indicates that Hindu themes were introduced into Mogul architecture two generations earlier than art historians thought.

It is a matter for scholarly debate. Mrs. Moynihan acknowledges that her interests are fairly ''removed from our life today,'' but bluntly dismisses the suggestion that her work is too rarefied to be appreciated by many people.

''I can't help that,'' she says, laughing.