The embodiment of the invention provides a quantum key distribution photon transmitting end, and belongs to the technical field of quantum. The quantum key distribution photon transmitting end comprises a light source chip and a spatial optical structure. The space optical structure comprises an optical filter, a diaphragm and a collimating convex lens; The light source chip is used for emitting photons with different polarization states; The diaphragm and the collimating convex lens are used for combining the photons with different polarization states into one beam and outputting the beam ina collimating manner, and eliminating additional information caused by different positions of the photons with different polarization states by utilizing an optical diffraction limit principle; And the optical filter is used for eliminating the difference of photons with different polarization states emitted by the light source chip on the frequency spectrum. The embodiment of the invention provides a quantum key distribution photon transmitting end. According to the integrated light source chip, the distance between the linearly polarized light sources is very small and can reach the magnitude of dozens of micrometers, so that the sizes of the diaphragm, the collimating convex lens and the optical filter can be designed to be very small correspondingly, and the overall structure of the photon emitting end can be miniaturized.