The present disclosure provides a trans-impedance amplifier, comprising: an equivalent secondary amplifier module, having an input end and an output end, wherein the input end is coupled to an optical diode and used for accessing an input voltage signal, and the output end is used for outputting a secondarily amplified first voltage signal; an inverting amplifier unit, coupled to the output end of the equivalent secondary amplifier module and used for accessing the first voltage signal and outputting an inverting amplified voltage signal, the inverting amplifier unit comprising a third N-type transistor and a fourth N-type transistor coupled to the third N-type transistor; and a feedback resistor, coupled to the input end of the equivalent secondary amplifier module and an output end of the inverting amplifier unit. The feedback resistor of the trans-impedance amplifier can be not restricted by original conditions, may increase resistance, reduce input noise and improve sensitivity.