The invention discloses an active power filter (APF) based on a high-frequency isolation AC-AC direct converter and an even harmonic modulation technology. A main circuit is composed of a push-pull forward high-frequency isolation AC-AC direct converter and a conventional reactive compensation capacitor, and reactive and harmonic integrated compensation can be performed. Compared to a conventional APF based on an inverter topology, the APF is not provided with a DC energy storage apparatus, only the conventional reactive compensation capacitor is used, and the price of the whole device is lower; at the same time, electrical isolation between the compensation capacitor and a power network side can be realized, and the reliability is higher; and the transformation ratio of a high-frequency transformer is changed, and under the objective conditions of the same voltage grade and the compensation capacitor, the compensation capacity of the whole device is of higher autonomous selectivity.