A full range boosting device includes two sheave intermittent mechanisms installed alternately in an up-down direction and a central gear. The two sheave intermittent mechanisms each include a dial gear, a driving dial fixed coaxially with the dial gear with no contact in axial direction, a dial round pin, a driven sheave having a radial slot, and a boosting plate fixedly connected to the driven sheave. Two dial gears are driven by the same central gear. When the driving dial of one of the sheave intermittent mechanisms rotates an angle of 1, its boosting plate rotates an angle to be boosted by a cooperation of the dial round pin and the radial slot. When the driving dial of the other sheave intermittent mechanism rotates an angle of (3601), its dial round pin is exactly located at a notch of the radial slot.