The surge mechanism of auxiliary power unit (APU) with load compressor was analyzed.To ensure load compressor's working stability

the method of controlling exit corrected flow less than the minimum stable work flow was put forward.When load compressor exit flow is less than 2%

compared with minimum stable flow

the surge control valve (SCV) used to avoid surge was opened.Proportion-integral-differential (PID) controller was designed to control the opening angle of SCV so as to avoid surge of load compressor

and make exit pressure of air meet certain requirements.Compared with APU actual test data

numerical simulation results show that the method can be used to ensure the load compressor's working stability.