An optical signal modulation circuit includes a laser (DFB), a modulator (EAM), and an operational amplifier. The laser (DFB) generates a laser to stimulate the modulator (EAM) to generate a photon-generated current (ip), a first port (a) of the modulator (EAM) is connected to a first input voltage (Vbias), a second port (b) of the modulator (EAM) is connected to an inverting input end of the operational amplifier, a non-inverting input end of the operational amplifier is connected to a second input voltage (Vin), and an output end of the operational amplifier is connected to the first port (a) of the modulator. In the modulation circuit, a photon-generated current (ip) of the EAM is fed back to the operational amplifier, to implement a linear relationship between the second input voltage (Vin) and the photon-generated current (ip) of the EAM, and obtain a linear EML transmission curve, namely, a high-linearity EML.