The invention discloses a method for satisfactorily controlling the net output power of a locomotive fuel cell system based on a peroxy ratio area. Through the analyses about the peroxy ratio characteristics of the locomotive fuel cell system, a peroxy ratio operation area is divided according to the satisfaction on the net output power of the system. On the basis, according to an overlapping ratio and an overlapping robustness index, a fuzzy subjection function is designed, as well as a fuzzy control rule and a fuzzy switching rule are formulated; the switchover without interference between a satisfactory fuzzy controller and a self-regulated PID (Proportion Integration Differentiation) controller is realized, so that the limitations that the net output power control of the traditional locomotive fuel cell system depends on an accurate systematic mathematic model too much and an optimal peroxy ratio track tracing method is easily affected by factors such as operation parameters, and noise interferences in the actual application, are solved; therefore, the satisfactory output of the net output power of the system is realized; the system stability is modified; the reliability of the locomotive fuel cell system is improved; and the service life of the system is prolonged.