Reciprocating compressor is an important equipment in industrial production. The crankshaft turns the thrust of the compressor piston rod into torque, which is an important component of the compressor. When reciprocating compressor works, there will be various forms of vibration such as torsion and bending. Therefore, the study of the crankshaft vibration becomes particularly important. Analyze the modal analysis of L type compressor crankshaft by using the finite element simulation. The first six order natural frequency and the corresponding mode of vibration of the crankshaft are obtained. And analyze the influence of the hollow and solid on the natural frequency and mode of vibration of the crankshaft. The results show: With the increase of vibration order, the natural frequency of the crankshaft increase. The crankshaft deformation is mainly bending at low frequency. The deformation of crankshaft is mainly composed of bending and torsional vibration at higher frequency. Moreover, the ends of solid crankshafts are less restrained. Extend the service life and performance of the crankshaft and other parts of the compressor by increasing the strength and stiffness of the crankshaft's local materials. And increasing the fillet radius at the transition point are adopted to reduce the deformation and torsion of the crankshaft.