The invention provides a working method of a thick-thin gravity auto-control type cutting device. The device comprises uprights and a fixed pressing plate, the fixed pressing plate is fixedly assembled between two uprights of two sides, lifting sleeves are assembled on the uprights in a sliding mode, and gravity blocks are connected to the lifting sleeves through ropes and rotating wheels; a lifting pressing plate is connected between two lifting sleeves of two sides, a cutting module is designed below the lifting pressing plate, a round blade which can rotate around its own axis is designed in the middle of the cutting module, the blade penetrates through a penetrating groove in the middle of the lifting pressing plate and extends deeply into a tool groove of the fixed pressing plate, and cloth to be cut runs from the middles of fixed pressing plate and the lifting pressing plate; an adjusting rod of the cutting module is fixedly connected with one lifting sleeve. The compaction force of the cloth in the device is kept constant when the cloth is cut, and meanwhile the adjusting rod conducts synchronous adjustment on the rotating speed of the blade, so that cutting edges of the cloth by the blade are same.