Abstract: A coherent photon analog-to-digital conversion device comprising an optical clock oscillation source, a sampled signal source, a photon sampling gate, a photoelectric detection module, an electrical sampling module, a phase detection module, a loop filter, and signal feedback links. By adjusting the optical clock oscillating source or the sampled signal source, the invention makes the two highly coherent, thereby reducing the clock jitter and greatly improving the sampling precision. It is very important for improving the performance of microwave photon systems that require high time accuracy and high sampling accuracy, such as microwave photon radar and optical communication systems.