A mobile generator comprises a tractor head, a generator body, a rack, a driving belt wheel, a transmission belt, a driven belt wheel, two bearing blocks, a universal joint coupling and three suspension connecting seats, wherein a rotating power output end of a tractor is connected with the driving belt wheel through the universal joint coupling, the two bearing blocks are symmetrically arranged on the rack, two ends of a rotating shaft of the driving belt wheel are arranged on bearing fixing seats through ball bearings respectively, the driven belt wheel is connected with a rotating shaft of the generator body, the transmission belt is connected with the driving belt wheel and the driven belt wheel, the three suspension connecting seats are fixed at the front end of the rack, and tail ends of three suspension arms are hinged to the three suspension connecting seats in a one-to-one correspondence manner. An idle agricultural machine can be fully used for driving the mobile generator for power generation, and the mobile generator can move flexibly, so that the power generation cost is reduced.