In the generator motor system for hoisting in mine exists self sustaining oscillation caused by the excitation saturation of generator.This self sustaining oscillation must be controlled within permissible range,otherwise it will leave hidden troubles for safety.This paper discussed the stabilizing transformer as a corrected link,which was used to restrict the range value of the self sustaining oscillation of the system and keep it in the permissible range of technical conditions so as to guarantee the stability of the system.