Juni M. Brown, who was convicted in February of beating his wife to death and sealing her body behind a pantry wall, was sentenced yesterday to a jail term of 20 years to life by a D.C. Superior Court judge.

During his trial, the journeyman carpenter denied government charges that he killed his wife, Francine, in May 1978. Brown testified that he was living in the Virgin Islands when his wife was slain.

But the jury, which convicted Brown on Feb. 23 of first-degree murder, believed the testimony of Brown's daughter Marian, who testified for the government that she saw her father strike her sleeping mother on the head three times with a heavy wooden club.

A second daughter, Eleanor, testified that both girls were then forced to help drag their mother's body down a flight of stairs to a walk-in pantry.

The government presented evidence in the trial that Brown had made a hole in the pantry wall, placed his wife's body in it and then covered the opening with plaster.

The woman's badly decomposed body was discovered by police and housing officials after neighbors complained of odors coming from the public housing apartment.