A non-isolated AC/DC converter having power factor correction, comprising an active switch connected to a waveform controller for control, and sequentially showing conduction, cut off, making the alternating current power supply pass through one circuit rectifier for rectifying and forming one positive half sine wave electricity supply, which passes through a voltage step-down circuit to proceed with decreasing the voltage, then passing through a filter/storage circuit for filtering and forming direct current power supply, which is stored on this filter/storage circuit, then releasing the energy and supplying electricity to the electricity end; as a transformer isn't required, the circuit volume can be reduced, lowering costs, raising circuit conversion rates and achieving power factor correction and increasing the lifespan of the transformer, moreover, through the waveform controller controlling the output waveform, the storage circuit utilizes a lower capacity capacitor to avoid using an electrolytic capacitor, thereby increasing the circuits lifespan.