Abstract: Aiming at the deficiency of the existing laser absorption rate measurement，a laser absorbing rate measuring device based on integrating sphere method was designed on the basis of the existing laser absorption rate measurement device.The light tube structure was added, the light source was monitored, and the light beam was modulated. The method of correlation detection and synchronous acquisition was adopted, which could effectively remove the influence on the measurement of background noise, detector noise and detection circuit noise. Furthermore, the influence of the light tube on the sample absorption rate was compared in experiment, and the experiments on multiple samples were carried out. The results show that the measurement error of the device can reach ±2% or less for the sample reflectance in the range of 10×10-6~10 000×10-6ppm,which indicates that highaccuracy measurement of laser absorption rate is achieved.