A theoretical model to simulate the transient response of tellurite-based erbium-doped fiber amplifier(EDTFA)is proposed,and the output response characteristics of EDTFA to a low frequency square-wave pulse signal are investigated by the finite difference method. When the amplified output signal is deformed,there is a fast transient response process corresponding to the leading-edge and falling-edge of input pulse signal with response time shorter than that of silica-based EDFA,indicating that EDTFA is suitable for the applications of pump-modulated and all optical-fiber switch. By studying the transient power changing of the surviving signal when one of two channels is switched off,the feasibility of pump adjustment is demonstrated to fast limit the output power excursion of the surviving one.