After nearly 40 years of development, the performance of InP/InGaAs single photon detectors have been improved significantly. The photon detection efficiency has reached 60%, the dark count rate is already within 20 kHz (-20 ℃), and the time jitter, afterpulse and photon counting rate are also further improved. At present, the time jitter is within 100ps, and the afterpulse probability is within 1%--5%, and the photon counting rate reaches GHz. Further performance improvement needs to consider the material system with smaller ionization coefficient ratio and excess noise, the device with multiple amplification gain and gain control, which can reduce the afterpulse while maintaining a certain device gain. The wavelength needs further expanded to provide more wavelength options. The chip needs internally integrated with self-quenching to simplify the circuit and realize free running single photon detection. And the chip could easy to integrate into single photon focal plane array at Geiger mode. In this paper, the latest development of InP / InGaAs single photon detectors based on conventional SAGCM (separated absorption, grading, charge, multiplication) and the new devices based on this technology are introduced.