Abstract: Surface thermal film measurement technology has advantages in turbomachinery internal flow dynamic measurement due to its high frequency response, good synchronization, and ability to accurately capture the continuous transient processes of boundary layer separation, transition and reattachment. The technique judges boundary layer properties by measuring the quasi wall shear force on the blade surface, and is a low invasive contact measurement. Currently, uncertainties about the interference of surface thermal film laying on the turbine boundary layer flow field have not been fully understood. In this paper, T106C, a high-lift low-pressure turbine blade, was taken as the research object. Based on the actual geometric characteristics of the hot film on the blade surface, a precise model was built to investigate the effect of hot film laying on the boundary layer characteristics and flow losses of the suction surface of the high-lift low-pressure turbine under wide operating conditions. The results show that hot film laying on the blade surface has little effect on the evolution of boundary layer on suction surface, but it can affect the separation of boundary layer, leading to the earlier location of separation bubble, the smaller size of separation bubble, the reduced flow loss, and more plump velocity distribution, the effect is more significant at high speed and low Reynolds number; The maximum error of suction surface boundary layer separation position caused by hot film laying is 1.12%, and the error of transition position is 0.64%. the reattachment position is most sensitive to hot film laying, and the maximum error is 1.8%.