Leonard B. Pouliot, 61, a retired federal administrator who had held senior posts in several agencies, pleaded guilty yesterday to filing false statements in connection with a consulting scheme operated through the U.S. Department of Agriculture's Graduate School.

The plea, entered here before U.S. District Court Judge Louis F. Oberdorfer, is the outgrowth of a grand jury investigation into operations of the school.

Assistant U.S. Attorney Charles J. Harkins Jr. said vouchers were submitted in the names of four fictitious employes of a consulting firm, called Interco, set up by Pouliot. He said the money, totaling $15,593, ultimately came from the Army.

Last spring the Agriculture Department's inspector general reported that the 54-year-old graduate school had acted improperly as a "pass-through contractor" to purchase supplies and hire consultants wanted by other agencies that wished to avoid cumbersome procurement regulations. The school's director, Edmund N. Fuller, resigned under pressure. He was not charged.

Pouliot, of 2111 Jefferson Davis Hwy., Arlington, held key posts in the Army and the Labor and State departments before leaving government to do consulting work. He faces a maximum penalty of five years in prison and $10,000 in fines. Sentencing was set for Jan. 24.