A new type of hybrid active power filter（HAPF） with high capacity and low cost is proposed. The active part is an inverter of the 3-phase 4-switch topology. The electrical model of the HAPF is developed by the output modeling. The filtering principle of the HAPF is studied to demonstrate the good performance theoretically. For the control of the HAPF， instruction currents are obtained by the ip -iqmethod based on the 3-phase instantaneous reactive power theory， and pulse-width modulation controlling signals are obtained by the improved triangle wave comparative method. The new type HAPF proposed is compared with the traditional HAPF with an inverter of 3-phase 6-switch topology. Simulation results show that the new type HAPF has the same performance of eliminating harmonics and compensating reactive power as the traditional HAPF， at less cost and power consumption. The new type HAPF is suitable for application in the high voltage and high capacity system.