The invention discloses a vibrating screen on-line control device self-adapting to feeding capacity, which belongs to the technical field of vibrating screen equipment and is used for changing the vibrating strength of a vibrating screen according to the change of the feeding capacity. According to the technical scheme, the vibrating screen on-line control device comprises a laser displacement sensor, a programmable controller and a frequency converter, wherein the laser displacement sensor is arranged on one side of a box body of the vibrating screen; a signal output end of the laser displacement sensor is connected with a signal input end of the programmable controller; an output end of the programmable controller is connected with the frequency converter; and the frequency converter is connected with a vibrating motor of the vibrating screen. The vibrating screen on-line control devices are arranged at symmetric positions on the two sides of the vibrating screen respectively, the change in feeding capacity is judged by measuring the amplitude change of the vibrating screen in a working process, and further the output frequency of each frequency converter is adjusted through the related programmable controller to change the vibrating frequency of the relatedvibrating motor and adjust the vibrating strength of the vibrating screen, so that the high-efficiency sieving of the vibrating screen for a material is kept, energy conservation and environmental protection are achieved, and the service life of the vibrating screen can be effectively prolonged.