The effect of temperature on the optical properties of biological tissue has been studied by using milk as the simulation sample. Optical properties of milk at 1100～1700 nm were measured by using the double integrating sphere technology in the temperature range of 25～40 ℃. Then the rule of change of optical properties with temperature was analyzed. The results show that the effect of temperature on scattering is greater than absorption. Obvious decrease can be observed with increasing temperature in the reduced scattering coefficient, which decreases by 10% at 40 ℃ compared to that at 25 ℃. And the change of absorptivity of milk with increasing temperature is small and complicated. The results were consistent with the reported results on the study of ex vivo tissue. This study provides valuable theoretical reference and practical experiences and leads to investigate the effect of temperature on optical properties of biological tissue.