Southern California Edison, which operates the plant, said it plans to eliminate 730 jobs. The company said operating costs at the plant are higher than at other similar facilities.
The San Onofre Nuclear Generating Station has been closed since January because of excessive wear to tubes that carry radioactive water.
The company vowed to fully maintain all safety commitments with the remaining 1,500 employees. The reductions are due to begin after September.
The Associated Press contributed to this report.