A power module includes a circuit board and a load group. The load group is installed on the circuit board. The load group includes a first-stage power conversion circuit, a second-stage power conversion circuit and plural loads. The first-stage power conversion circuit converts an input voltage into a transition voltage. The second-stage power conversion circuit converts the transition voltage into a driving voltage. A rated value of the first input voltage is higher than twice a rated value of the transition voltage. A rated value of the driving voltage is lower than a half of the rated value of the transition voltage. The distance between the input terminal of the second-stage power conversion circuit and the output terminal of the first-stage power conversion circuit is smaller than the distance between the input terminal of the first-stage power conversion circuit and each edge of the circuit board.