The invention discloses a positron annihilation lifetime spectrometer based on a silicon photomultiplier (SiPM), and the lifetime spectrometer comprises a SiPM detector module, an analog signal processing module, a timing and discrimination circuit module, a digital acquisition circuit module, a matching unit and a low voltage power supply module, wherein the SiPM detector receives gamma photons and generates scintillation light, which is converted into a photoelectric signal by the SiPM; the photoelectric signal is processed into a pulse signal through further amplification, noise reduction and the like by the analog signal processing module; the pulse signal is timed and discriminated by the timing and discrimination circuit module to obtain position information, energy information and time information of the gamma photons; the information is acquired by the digital acquisition circuit module and filtered by the matching unit to a meeting event; and all the modules are powered by thelow voltage power supply module. The positron annihilation lifetime spectrometer can improve measurement accuracy, reduce measurement time, greatly reduce cost, reduce power supply requirements and simplify the spectrometer structure.