The developing of quantum information technology calls for single photon detector to have higher capability. As a new-style single photon detector, quantum-dot based single photon detector has good potential. A single photon detector based on quantum-dot field effect transistor (QDFET) is researched. The photoconductive gain mechanism of QDFET is introduced. Then the material is chosen and the structure is designed. It′s laid stress on the experimental analysis of photoconductance quantization and noise equations. The results indicate that the single photon detection based on QDFET has great characteristic in sensitivity, photon response and photon resolution ratio.