Abstract: To study the vibration characteristics of mimic crankshaft in working mode, we used finite element analysis software ANSYS to analyze the dynamic characteristics of crankshaft in the design stage of the mud pump. In order to simulate the crankshaft bearing support boundary condition accurately, we designed an experimental device of the bearing stiffness. Then the spring shafting finite element model was built, and we got the first 4 natural frequencies and mode shapes, which supplied theories for designation and optimization of the mud pump crankshaft in drilling.