In this paper, we present a method for measuring weak light pulses using a single-photon detector, with a focus on detecting non-synchronized repetitive pulsed light. The proposed approach, based on interval distribution counting, enables accurate reconstruction of both the repetition rate and phase of weak pulses, facilitating the determination of the average photon number and pulse width. Specifically, the error in reconstructing the repetition rate is below ±0.01%, while the error in measuring the photon number per pulse remains below ±0.8%.