The heavy-duty crankshaft is one of the key components of the power end of a large-scale diaphragm pump,and its strength is critical to the smooth operation of the entire power end.Moreover,the failure form of the heavy-duty crankshaft is often fatigue damage caused by stress concentration at the fillet.To solve this problem,the morphology of the crankshaft was from the perspective of the structural characteristics of the fillets.The most dangerous working condition during the operation of the crankshaft was determined by the static strength stress analysis,which was used as the calculation condition for the subsequent optimization.Then,the maximum stress value at each fillets and the maximum deformation of crankshaft were taken as the optimization objectives,the structural parameters at the fillet were taken as the design variables for the experimental design.According to the experimental results,the response surface model of the optimization objective with respect to the design variables were constructed based on Kriging interpolation method.Finally,a multi-objective optimization model were established and the multi-objective genetic algorithm was applied to find non-dominated set of solution.The final results show that the inclined angle of the inclined planes at crank arms of crankshaft after topography optimization is close to 90°,which provides a certain reference for the structural design of heavy-duty crankshaft in the future.