By taking PV-type InSb detector for example, the dynamics model describing the carriers transportion is established, and then the function relation between the potovoltage and the incident light power density is obtained. Thus, a new method to eliminate the disturbance of intense background radiation to PV-type InSb detector is proposed. Contrasting with the conventional zero-set method, such a new method can be applicable to more powerful background radiation accurately. Furthermore, the validity of the new method and the rationality of the theoretical model are testified experi mentally．