Susan E. Saxe yesterday received a 10 to 12 year prison term after entering a plea of guilty to two charges of robbery and one charge of manslaughter.

Massachusetts Superior Court Chief Justice Walter H. McLaughlin sentenced Saxe to the term which she will serve concurrently with a previous 10-year sentence.

Saxe was scheduled to go on trial for a second time next week. Her first trial in October ended in a hung jury.

In a statement Saxe issued yesterday, she said, "I plead guilty today for one reason and one reason alone--that it is the surest and quickest way to end the hold this state will have on my life and my personal freedom. I have been harassed, hounded and villified by the state for six and a half years and have been imprisoned for two years. I do not recognize the right of the state to a single day of my life, but I do recognize its power to take that and more. I will never abandon my political commitments in exchange for favors from the system."

Saxe's attorney, Nancy Gertner, said yesterday, "We made a good deal. Facing a practical choice, we made a practical decision." Saxe was scheduled to go before Judge James Roy, who Gertner said, "has no reputation for compassion."

As part of her guilty plea, Saxe admitted to taking part in a 1970 bank robbery in which a Boston policeman was killed. John T. Gaffney, first assistant district attorney, said yesterday Saxe was allowed to receive a reduced charge of manslaughter because she felt shooting the patrolman was not warranted in the bank robbery.

Gaffney said "It vindicated the district attorney's office and the criminal justice system because up till then she denied she had taken part in the bank robbery. The media criticized us for prosecuting Susan Saxe by saying we were just prosecuting her because she was an anti-war activist."

Leslie Kagan, a member of the Susan Saxe Defense Committee, denied Gaffney's claim yesterday. "There was no way it is a victory for the prosecution. Gaffney has yet to prove Susan Saxe guilty before a jury, or even guilty of anything. We understand he was afraid of another trial and therefore he initiated the plea bargaining," Kagan said.

She said "The Defense Committee all felt it was a wise decision to enter a guilty plea given political and legal realities of the new judge, of the probability of less peremptory challenges and the climate within the legal system against Susan Saxe, we all agreed it made sense."

Saxe was apprehended in March 1975 after being on the FBI's 10 Most Wanted List for five years.