Abstract: The number and position of force-measuring couplers are uncertain in the longitudinal load on-track test of 10,000 tons of heavy haul train.The longitudinal load-time history of 10,000 tons heavy-haul train including 16 cars on the coal transportation railway is obtained according to the on-track test.The maximum value, root mean square value and standard deviation of tensile and compressive loads are extracted to analyze the load characteristics.Extrapolation of quantile based on kernel density estimation was used to obtain the spectral damage of different gondola cars.The principal component analysis method was used to reduce the dimension of the longitudinal load characterization parameters into 4 comprehensive characterization parameters.Using the hierarchical clustering method, the common characteristics of longitudinal loads of different gondola cars were statistically analyzed, and the layout scheme of 2～16 types of force-measuring couplers was obtained.Considering the factors of principal component analysis, hierarchical clustering and the position of gondola cars, the optimization results of the number and distribution of force-measuring couplers are obtained: the minimum number of force-measuring couplers is 4,which can meet the test requirements.These couplers are located at the front and rear of the slave locomotive, the rear of the train, and between the slave locomotive and tail locomotive.