Prince George's County public schools expelled 174 students from secondary school last year for possession of weapons and drugs, compared with only one student in the 1981-82 academic year, according to figures released yesterday by school officials.

Officials expressed surprise that the rate of expulsions did not decline over the course of the year as their expulsion policy--the toughest in the Washington area--received a great deal of public attention.

When they adopted the policy last fall, school officials predicted that the number of expulsions would tail off as students became aware of the tough new rules.

They released figures in January showing 60 students had been expelled thus far in the year. There were 58,300 secondary school students in county schools.

Board member Angelo Castelli, chief author of the original policy, defended the high number of expulsions.

"Out of 58,000 students, that's not too bad," Castelli said last night during a break in the regular board meeting. "I think, basically, it is working.

"Our schools are becoming much safer," he added. "We have listened to all the appeals brought before the board. The board has taken the position that they want the policy strictly enforced."

Asked why the expulsion rate had not decreased over the year, Castelli said, "I don't think people took us seriously. The point is being driven home. I think you'll see a difference this year."

"I don't have any idea why it hasn't slowed down," Clark A. Estep, executive assistant to school superintendent Edward Feeney, said yesterday. "A lot of folks have the idea that 'I'm from Missouri, you have to show me.' "

Estep is responsible for conducting conferences with parents and students charged with code infractions before an expulsion recommendation is made to Feeney.

One hundred seven of the expulsions were for weapons possession, while the remainder were for students caught with drugs or alcohol on school grounds, according to school officials.

The expulsion policy, an amendment to the school Code of Student Conduct passed almost exactly a year ago, requires expulsion for the first possession of any weapon or the second possession of alcohol or drugs.

"We even expelled students in summer school," said a school spokesman.

At the time the policy was approved, any expulsion for weapons possession was permanent unless the school board agreed to reinstate the student on appeal.

Students expelled for drugs or alcohol could apply for readmission after proving successful completion of an acceptable rehabilitation program.

At least half the students expelled before March 30 appealed their cases to the board, causing numerous lengthy board meetings to consider student appeals.

On March 31, the school board amended the policy to allow students to apply to the superintendent for readmission after being out for the remainder of the term in which they are expelled, plus an additional semester.

Estep said the number of appeals dropped sharply after the board's amendment.

He said he expected the number of expulsions to drop this year, but other school officials predicted privately that the number would stay at least the same.