The invention discloses an average photocurrent monitoring circuit supporting APD application. The circuit is characterized in that the circuit comprises a main current circuit and a secondary current circuit; the main current circuit comprises a normally-biased photodiode; the anode of the photodiode is accessed to an input end of a trans-impedance amplifier; the secondary current circuit comprises a virtual trans-impedance amplifier which is the same with the trans-impedance amplifier, a controlled current mirror and a differential amplifier module; the input end of the trans-impedance amplifier is connected with a negative input end of the differential amplifier module; an input end of the virtual trans-impedance amplifier is connected with a positive input end of the differential amplifier module; and a virtual output end of the controlled current mirror is connected with the input end of the virtual trans-impedance amplifier, and a control end of the controlled current mirror is connected with a differential output end of the differential amplifier module. By the scheme, photocurrent monitoring effect of the secondary current circuit can be realized by the use of a low-voltage circuit without the influence of bias voltage of the photodiode; and the monitoring circuit is greatly compatible with different biased photodiodes so as to save costs.