The invention relates to a power conversion device which comprises a transformer, a switch, a sensing circuit, a feedback circuit and a control circuit, wherein the transformer receives an input voltage and converts the input voltage to generate an output voltage; the switch is coupled with the transformer to control the current of the transformer; the sensing circuit is coupled with the switch and detects a current of the switch to generate a sensing signal; the feedback circuit is coupled with the transformer and generates a feedback signal according to the output voltage; and the control circuit is coupled with the switch, the sensing circuit and the feedback circuit and executes division on the sensing signal and the feedback signal to determine a working period of a switching signal to generate the switching signal, and the switching signal is used for controlling the switch to further control the current of the transformer. Thus, the power conversion device can be effectively digitized, thereby the complexity of the conversion device is further reduced and the stability of the conversion device is increaded.