CNC trilateral plate bevelling machine is processing equipment which is finished one edge bevelling and in two long side edges up-down bevel and truncated edge beveling in one time feeding. When the plate lifting to the conveying platform ,to input parameters in the CNC system, the machine each milling unit feed and lock the plate in place, and the plate is centring and positioning automatically, and to draw the plate back to end of the machine after processing the end of the plate to transport the plate in a straight line through synchronous finish processing up- down bevel and truncated edge.