A new theoretical model of an RC circuit is proposed for prediction problem of laser induced biological tissue temperature rise. The RC circuit system function and unit impulse response are deduced based on Kirchhoff′s voltage law (KVL). Then RC circuit zero state response model is deduced from the convolution of unit impulse response and rectangle input signal. The two model constant parameters are calculated from experimental results of the laser irradiated bio-tissues temperature. Two model parameter calculation methods are proposed and simulated. Theoretical calculation and experimental results show that the temperature response curves are consistent. Relative error ranges of liver and muscle tissue peak temperature are -0.0557 ℃~-0.0025 ℃ and 0.0139 ℃～0.0641 ℃ respectively, and average relative error ranges of the temperature curve are 0.55%～2.39% and 0.38%～0.99% respectively. This method needs less parameters and is more precise than classical Pennes bio-heat transfer equation model, which provides a new method for laser and bio-tissues photothermal effect research.