A single photon avalanche diode was proposed based on the standard 0.35μm CMOS technology. The single photon avalanche diode was with the p+n well junction structure, the guard ring and deep n-well structures were introduced to improve the performance of the device. The influence of the diffusion n-well guard ring width on the breakdown characteristics was investigated. The typical characteristics such as electric field distribution, breakdown characteristics, photon detection efficiency and frequency response were analyzed. The simulation results show that, when the diameter of the proposed single photon avalanche diode device is 10 μm and the diffusion of n-wells width of the guard ring structure is 1 μm, the avalanche breakdown voltage is 13.2 V, the 3 dB bandwidth is up to 1.6 GHz. The maximal photon detection efficiency is as high as 52% and 55% when the excess bias voltage is 1 V and 2 V, respectively. The best responsivity is obtained within the spectral range wavelength of 500～800 nm, the peak unit responsivity is 0.45 A/W at the wavelength of 680 nm.