In order to establish a defect detection system of fused quartz and improve laser-induced damage threshold, a device of insitu measuring fused quartz damage characteristics is designed. It consists of two parts, photothermal scanning measurement and Raman spectral measurement. The experimental results show that, the equipment can not only measure fixed point damage characteristics of fused quartz, but also get the absorption characteristics anddefect distribution of fused quartz by two-dimensional photothermal scanning. Moreover, the Raman spectral information and material modification information caused by laser irradiation could be obtained insitu through the micro Raman spectrum measurement module of the device, which is of great significance to control and evaluate the laser damage characteristics of fused quartz effectively.