Abstract: In this paper,a novel near-infrared wide-spectrum CMOS single-photon avalanche diode detector（SPAD） structure is proposed.The primary avalanche region is formed between deep Nwell and P-epitaxial layer,which improves the detection efficiency of near-infrared shortwave photons.Meanwhile,there exists two secondary avalanche zones arranged in a symmetrical ring in the deep Nwell region,im-proving the spectral response range.The proposed novel device structure and the traditional P +/Nwell structure were compared by TCAD simulation in 0.18μm CMOS process.The simulation results show the new SPAD device arrives high photon detection efficiency of 19.9% at the 850 nm near-infrared short wavelength,which is about 5 times that of the P +/Nwell structure,and can respond to single photon within a wide spectral detection range of 300nm-1000 nm.In addition,due to low field strength in the avalanche region,the new SPAD structure is slightly affected by the band-to-band tunneling（BTBT）effect,thus the dark count rate（DCR） varies very little with the excess bias voltage and the DCR is lower than that of the P +/Nwell structure at temperatures below 20℃.