Abstract: The bending of the collector tube in the solar trough thermal power plant will cause the spillage loss of the concentrated energy,which needs to be measured and analyzed. The bending measurement method of the collector tube based on the UAV photography is proposed. The UAV is equipped with high-resolution visible camera to realize the images acquisition of the collector tubes. Based on the edge detection algorithm,the images of the collector tubes are processed,and finally the bending value of the collector tubes is obtained. Based on the ray tracing theory,the mathematical model of the concentrating process of the solar trough concentrator is established,and the calculation formulas of the spillage loss of the bended collector tube is deduced. Three kinds of collector tubes with different bending values are selected for measurement experiments. The measured maximum bending values are1.23,7.75,18.79 mm respectively,the average measurement error is ±0.75 mm,and the corresponding spillage losses are 0.02%,0.57%,3.72% respectively. The results show that when the collector tube bending amount is larger,it will cause larger overflow loss.