After months of preparation and some last-minute political maneuvering, the Montgomery County Education Association asked a circuit court judge yesterday to void the four-year contract renewal granted to school superintendent Charles M. Bernardo by the Board of Education last June.

The CEA charges in a four-page brief that the Board of Education violated state statutes governing the hiring of superintendents when it originally hired Bernardo in September 1975 and that it further ignore the state guidelines by renewing his contract last June.

The County Education Association, represents 6,350 Montgomery County teachers and is actively supporting four candidates in the November school board election. Henry Heller, the association's president, said yesterday that if the court agrees with the MCEA's interpretation of the law, consideration of Bernardo's contract would be postponed until next February-after the new school board has been seated.

County school officials and board members say that the board was advised by lawyers coomissioned to study the problem that it was on solid legal ground when Bernardo was rehired.

Bernardo, whose forceful style and innovative computer-assisted teaching programs in math and other subject have made him the subject of a growing controversy in county schools, said that he had "every confidence that the legal opinion of the board will upheld."

Saying that state school superintendent David Hornbeck "has already ruled that my rehiring was legal in every respect," Bernardo said that "the staff and general public recognize (my work) for what it is and are behind me."

At issue in the contractis a state statute that specifies that superintendents should be hired in February for four-year terms beginning the following July 1. In the case of a vacancy, the law states, an interim superintendent should be appointed to serve until the following July 1.

Under that law, Bernardo who was hired permanently in September 1975 to fill a vacancy, and rehired last june, would have been given illegal contracts in both cases. However, the MCEA and the board disagree on whether the law applied to Bernardo's contracts. Board officials argue that the relevant provisions of the law did not take effect until July 1 of this year, when a new legislative act clarifying the statute became law.

The MCEA delayed the filing of its brief for several days last week while Heller unsuccessfully tried to persuade several school board candidates and board members to join in the action as coplantiffs or friends of the court.