A power conversion apparatus, which converts power of a DC power supply and provides it to the loading, includes a transformer, an electronic switch, a leakage energy recycling circuit, and a output circuit. The transformer has a primary winding, which receives the power, and a secondary winding, which outputs the converted power. An end of the electronic switch is electrically connected to the primary winding; another end thereof is electrically connected to the DC power supply. The leakage energy recycling circuit is electrically connected to the primary winding, and repeatedly and alternatively outputs power of positive and negative voltage. The circuit receives and stores leakage energy of the transformer, and feedbacks it to the transformer. The output circuit is electrically connected to the secondary winding to receive the converted power and to provide it to the loading.