In order to achieve high integration and efficient output of optoelectronic information devices, and improve the optoelectronic information processing ability, a four-channel filter based on two-dimensional photonic crystals is designed. According to the coupling principle of four point defect microcavities and line defect waveguides, the reflection heterojunction is introduced and the distance between the micro-cavity and the reflection junction is adjusted to improve the output efficiency. The wavelength division multiplexing function of four-wavelength of 1 403, 1 426, 1 449 and 1 508 nm is simulated. The simulation results show that the device can achieve efficient transmission, the transmission of all four wavelengths is more than 95%, the insertion loss is less than 0.23 dB, and the cross-talk between channels is less than -8.7 dB.