A vertical crusher for bagasse comprises a rack, a crushing cylinder and a crushing spindle, wherein the crushing cylinder is vertically mounted on the rack; two ends of the crushing cylinder are bothprovided with an end cap, and the end cap at the top of the crushing cylinder is provided with a feed inlet; the bottom end of the crushing cylinder is provided with a discharge port; the crushing spindle is installed in the crushing cylinder through a bearing seat; a driving device is connected to one end of the crushing spindle; a plurality of mounting flanges are mounted on the crushing spindle in the crushing cylinder; the mounting flange is uniformly provided with a plurality of circular holes with the crushing spindle as the symcenter, and crushing knife mounting shafts are installed inthe circular holes; and a plurality of crushing knives are installed on the crushing knife mounting shafts. The vertical crusher of the invention has advantages of high crushing efficiency, low energy consumption and small particle size of bagasse after crushing.