Abstract: Based on structural features of rotary classifier with straight blades for MPS89k medium speed pulverizer, a new rotary coal classifier with variable cross section and bowed-twisted rotor blades was proposed, to which numerical simulation was performed using Fluent software so as to analyze its comprehensive performance under different conditions of blade structures, and obtain optimum structural parameters of the rotor blade. Results show that for the new coal classier, the optimal twist angle of its rotor blade is 25°, in which case the flow field following the rotor blade is evenly distributed, the air return at both ends of the stator blade is reduced, the erosive wear at bottom of the stator blade is alleviated, and therefore the survice life of the classifier will be elongated. Under the optimmum conditions of rotor blade structure, the outlet fineness of pulverized coal is 1.39%, the comprehensive separation efficiency is 95.83%, the air resistance in solid-gas two-phase flow of the classifier is 1 174 Pa, which can satisfy the requirements of actual engineering projects.