The photon detection technology is a hot area in the low light detection. The working principle, basic structure and performance characteristics of SPM (silicon photo multipliers) detector are introduced, in order to verify the photon detection performance and photon resolution ability of SPM detector, SPM photon detection circuit using high speed transconducance amplifier is designed, and the photon detection experiment is studied. The experimental results show that SPM detector has a better photon resolution property.