Twenty-two students have been expelled from school in Prince George's County so far this year -- compared to one expulsion throughout the last school year--and another 22 are making their way through the expulsion process, according to school officials.

Students are feeling the effect of a new policy that requires junior high and high schools to expel pupils found possessing weapons or drugs, in some cases on the first offense. Students are finally getting the word, said school superintendent Edward J. Feeney, that, "we really mean it."

"I think the policy has a sobering effect on everyone," said Crossland High School principal Joseph A. Hairston, who has expelled three students. "There has been a redefinition of what the school stands for."

The new policy on expulsions, adopted by the Prince George's County school board last August, requires a principal to request the superintendent expel any secondary school student found with a weapon. A student found with alcohol or drugs is suspended for five days the first time, but a second offender is expelled. First-offender students possessing large quantities of drugs with the intent to distribute are also recommended for expulsion.

In the case of drug users, the superintendent may revoke an expulsion after a student has been out of school for one semester and has been certified in a drug rehabilitation program.

Clark A. Estep, assistant to the superintendent, holds a conference with the offending student and his or her parents before recommending action by the superintendent. Of 27 requests from principals, 22 have resulted in expulsion.

Four parties have appealed to the school board. Other parents have reacted to the expulsions in a variety of ways, Estep said.

"I had one father comment that he was glad to see the school system tighten down, even though it was his kid that was penalized," Estep said. That parent placed his child in a drug program.

A few other parents have moved their children to schools in the District, Estep noted.

Supt. Feeney, who had some reservations about the mandatory nature of the expulsions, said yesterday he is looking into developing a program for students caught with weapons, similar to the drug rehabilitation course.

"You would eventually like to be able to say that you've saved the person," Feeney said.

Board member Angelo Castelli, father of the new policy, said the pain of expulsions will lead to improved discipline.

"If expulsions are dramatically up, then that's the way it should be," he said.

School principal Hairston generally agreed.

"Good wouldn't be the term," said Hairston, "but effective is. Somebody has got to do the job."

The expulsions are almost evenly divided between black and white students, according to school figures, with 12 black students and 10 whites leaving school. Black students received a disproportionate share of suspensions compared to their numbers during the 1980-81 school year, a statistic cited by the county NAACP in its desegregation lawsuit filed in September 1981.