The study about the internal flow field of the oil-free scroll compressor has an important influence on the performance of the oil-free scroll compressor. A three-dimensional unsteady CFD numerical simulation of the internal flow field of an oil-free scroll compressor was established.Taking air as a working medium, dynamic mesh technology was applied to analyze the flow law and state distribution of the working fluid in the working chamber, and mass flow at different motor speeds. Analysis results show that the mass flow of the working fluid increases as the spindle speed up; during the operation of the compressor, as the main shaft rotates, the pressure and temperature of the working gas in the working chamber gradually increase and unevenly distributed.