WASHINGTON (AP) _ President Reagan said Thursday he will nominate Martha Graham, a pioneer of modern dance, as a member of the National Council on the Arts.

If confirmed by the Senate as expected, she will succeed orchestra conductor Erich Leinsdorf, serving the remainder of a term that will expire next year.

Miss Graham, 90, is founder and director of the Martha Graham Dance Company in New York.

She has received many awards, including the Distinguished Service to the Arts Award of the National Institute of Arts and Letters in 1970, the Presidential Medal of Freedom in 1976 and the Kennedy Center Achievement Honor in 1979.