Structure and moving trajectory of reel device which was the key parts of silage harvest machine mower table were analyzed. Guide rail curves of reel device were optimized by using computer aided design software. The tooth shape trajectory was simulated to fit the silage harvester to operate. The wheel speed ratio interval for the silage harvester to work normally was (0.78, ∞). It could provide theoretical reference, improve the working efficiency and enhance the performance of silage harvester.