The invention discloses a frictional force demonstrator which comprises the components of a horizontal table, a sliding device, a displacement sensor, a motor pulling device, a friction block, a forcemeasuring device, a pointer, a first display device, a switch panel, a second display device, a chute, an amplifying device, an image acquisition device, a computer, a projector, a printer, a blackboard writing device, a projection device and a horizontal measuring device. According to the frictional force demonstrator, according to the indicating condition of the pointer on a scale plate, and amplifying a relation between a slide block pulling time by the motor pulling device and a movement distance of the slide block on the first display device, a relative motion trend direction and a relative motion direction are determined through observing a burr direction on a burr flexible plate by a magnifier, and furthermore the burr direction on the burr flexible plate in a continuous time period in the relative motion trend and the relative movement is acquired through the image acquisition device, and furthermore a burr direction image is amplified and displayed on a projection cloth curtain, thereby quickly, visually and accurately demonstrating the frictional force direction and the relative movement trend direction.