Abstract: Experiments and theory analysis were carried out to investigate the characteristics of temperature measurement using thermal imager for curved surface.According to the theory of infrared thermometry techniques,the infrared radiation characteristics of curved surface essentially have no difference with flat surface,both of which can be described by the same mathematics expression.The essential reason which induces the measuring error of infrared thermal imagery for curved surface is that equivalent face of the measured surface no longer satisfies the diffuse body hypothesis,owing to too large included angle of the normal direction of curved surface and the measuring direction of infrared thermal imagery.The temperature measuring accuracy can be improved by measuring the local emissivity for the region where the diffuse body hypothesis is invalid for its equivalent face.