A high-order active N-path bandpass filter with harmonic rejection was designed using a three-stage second-order N-path filter unit. By inserting a negative resistance and a gyrator between the second and third stages, the Q factor, bandwidth and linearity of the filter were improved. Two clock signal with Ts/6 phase offset were used to control the second-order N-path filter unit in the final stage, which could effectively reject the third-order harmonics. The filter was designed in a 0.18-μm CMOS process. Simulation results showed that the maximum gain of the filter was 20.12 dB, the center frequency could be adjusted between 0.1 to 1 GHz, the out-of-band rejection was up to 50.2 dB@700 MHz, the third harmonic rejection was greater than 40 dB, the noise figure was in the rage of 4.71 dB to 6.9 dB, and the out-of-band input third-order intermodulation point (IIP3) was 16.3 dBm@50 MHz.