Abstract: The present disclosure provides a momentum-matching and band-alignment van der Waals (vdW) infrared photodetector and a fabrication method thereof. The photodetector includes a substrate, a dielectric layer, a Bi2O2Se layer, a black phosphorus (BP) layer, a metal source and a metal drain. The fabrication method includes: transferring, in a wet manner, the Bi2O2Se layer grown on the mica substrate onto the substrate having the dielectric layer, transferring the mechanically exfoliated BP layer through a micro-region fixed-point transfer device onto the Bi2O2Se layer, and separately fabricating the metal source and the metal drain on the Bi2O2Se layer and the BP layer by processes such as electron beam exposure and electron beam evaporation, thereby forming the momentum-matching and band-alignment vdW infrared photodetector having a vertical structure.