The invention discloses an ambient light resisting circuit and method, and the circuit comprises a light-emitting circuit, an optical signal receiving circuit, a photovoltaic conversion circuit, a sampling holding circuit, and a subtracter. The input end of the light-emitting circuit receives an external input signal, and the light-emitting circuit transmits a first optical signal to the optical signal receiving circuit. The optical signal receiving circuit receives the first optical signal from the light-emitting circuit, and a second optical signal from the external ambient light. The output end of the optical signal receiving circuit is connected with the photovoltaic conversion circuit. The output end of the photovoltaic conversion circuit is connected with an inverted phase input end of the subtracter, and the second output end of the photovoltaic conversion circuit is connected with the sampling holding circuit. The output end of the sampling holding circuit is connected with the in-phase input end of the subtracter. The output end of the subtracter outputs a result. The circuit achieves the inhibition of ambient light, effectively enlarges the application range, and improves the capability of resisting environment interferences.