Abstract: The traditional mixing process of polyvinyl chloride (PVC) slush molding powder was improved by adding mixing phase at room temperature and optimizing the key processing parameters of the new phase. Different influences on the homodisperse of inorganic nanoparticles between the new process and the traditional process were compared using active CaCO₃ with particle sizes of 60-80 nm and rutile titanium dioxide with particle sizes of 100-120 nm as raw materials. Besides, the effects of different process parameters of mixing at room temperature on material properties such as the fluidity of slush molding powder, mechanical property and thermostability of slush molded skins were analyzed quantitatively. The results show that the optimized mixing process can enhance the uniform dispersibility of nanoparticles in PVC slush molded skins and the fluidity of PVC slush molding powder, and it can improve the elongation at break, thermostability and resistance of hot air loss of PVC slush molded skins.