The spherical plain bearing test bench is a necessary detecting equipment in the research process of self-lubricating spherical plain bearings.The varying environmental temperatures cause the thermal deformation of the wear-depth detecting system of bearing test benches and then affect the accuracy of the wear-depth detecting data.However,few researches about the spherical plain bearing test benches can be found with the implementation of the detecting error compensation.Based on the self-made modular spherical plain bearing test bench,two main causes of thermal errors,the friction heat of bearings and the environmental temperature variation,are analysed.The thermal errors caused by the friction heat of bearings are calculated,and the thermal deformation of the wear-depth detecting system caused by the varying environmental temperatures is detected.In view of the above results,the environmental temperature variation is the main cause of the two error factors.When the environmental temperatures rise is 10.3 ℃,the thermal deformation is approximately 0.01 mm.In addition,the comprehensive compensating model of the thermal error of the wear-depth detecting system is built by multiple linear regression (MLR) and time series analysis.Compared with the detecting data of the thermal errors,the comprehensive compensating model has higher fitting precision,and the maximum residual is only 1 μm.A comprehensive compensating model of the thermal error of the wear-depth detecting system is proposed,which provides a theoretical basis for the improvement of the real-time wear-depth detecting precision of the spherical plain bearing test bench.