Abstract: The coupler-head vertical constrain effect between two rear connected couplers under locomotive pulling forces has some influences on the locomotive axle load transfer. Such rear coupler vertical constrain effect is assumed as a linear vertical spring, and the equation for calculating the locomotive axle load transfer is obtained by the car body and by the bogie force analysis considering the coupler vertical constrain effect. Then the general and efficient locomotive axle load transfer calculation method is developed on the grounds of the stiffness matrix of locomotive vertical dynamic equations. The influences of the coupler vertical constrain effect and locomotive structural parameters on the axle load transfer are discussed by the proposed method. The results show that, the vertical restraint effect of the coupler has an obvious influence on the axle load transfer of the locomotive, and the control value of the equivalent restraint stiffness of the coupler tail can be determined according to the actual measured value of the free end coupler lift of a HX series locomotive. And the locomotive structural parameters also have some influences, the axle load transfer during traction can be reduced by reducing the vertical stiffness of the first system of the locomotive, increasing the vertical stiffness of the second system and reducing the height of the traction point.