The accumulation of micro-damage such as matrix crack and fiber fracture in car bon fiber reinforced polymer (CFRP) under cyclic loading will seriou sly affect the mechanical properties of CFRP.The size of micro-damage is small and the locati ons of micro-damage are scattered,which are difficult to be accurately identified by tr aditional nondestructive testing methods.Laser ultrasonic detection technology has the ad vantages of non-contact,fast detection speed,wide measurement range,et al.Especially combine d with the advantages of laser long distance excitation and large angle incidence,it has a great potential in the damage detection of large size and curved structure materials.Based on the thermoelastic effect of laser,the generation process and propagation characteristics of ultra sonic wave in CFRP are systematically studied on the basis of analyzing the distribution of te mperature,stress and displacement field after laser is applied to CFRP.Through the analysis and comparison of ultrasonic echo signals with defects in different places in CFRP,t he corresponding relationship between defect position and echo signal characteristics is obtained,so as to re alize the reverse performance of the key information of defect position in CFRP from the echo sign al characteristics.