Abstract: In order to improve the service life of rotary blade,reduce energy consumption,cutting edge of rotary blade was designed based on archimedes spiral cord.Rotary blade and knife roller were optimized.The archimedes spiral cord was used to cutting edge to optimize stress condition.Angle α between the end of edge-curves and folded line had great effect on sidelong edge,so angle α was optimized by statics analysis and energy consumption.The result showed thatwhile the angle α was 57°,the energy consumption was lowest and strength was enough.Knife rollers were symenetrically arranged, with 3 helixes for rotary blade. The test for the optimization of rotary blade and knife roller was taken, the result showed that optimization could reduce heat quantity and energy consumption.