Because the piston volume of a scroll compressor with variable base circle involute can be reduced under the premise of obtaining the same cooling capacity, it can satisfy the compact and lightweight requirements of vehicle air conditioning compressors. To improve the isentropic and volumetric efficiencies of the scroll compressor, a mathematical and geometric model of the scroll disc with a variable base circle involute was established. With the variable index k and the modified increment δ₀ as variables, the internal flow field of the scroll compressor is numerically simulated, and fluid dynamic analysis is conducted. The numerical results show that when the parameters of the variable base circle line are k=1 and δ₀=-0.03 mm, the specific dissipation rate of the fluid in the compressor working chamber is 180.28 s^-1, which is 103.11 s^-1 lower than the 283.39 s^-1 of the flow field in the fixed base circle compressor. The isentropic efficiency of the scroll compressor can be improved by reducing energy loss due to the turbulent kinetic energy dissipation. The performance of the scroll compressor for electric vehicle air-conditioning was tested. Compared with the fixed base circle scroll compressor, the input power of the variable base circle scroll compressor with k=1 and δ₀=-0.03 mm decreases by 1.392%, and the performance coefficient COP_el increases by 4.204%.