Quantum key distribution (QKD) is easy to lose information carriers in channels, so the limited communication distance and key generation rate are the main bottlenecks of its application. Generally, the key rate is limited by the channel transmission rate. The proposed phase-matching quantum key distribution (PM-QKD) protocol overcomes the linear key rate constraint that the secure key rate is proportional to the square root of the transmission rate. Although the PM-QKD protocol can guarantee the security of the detector, there are still some defects in the light source. In the PM-QKD protocol, it is generally assumed that the light source is an ideal coherent state, which is not consistent with the actual QKD system, resulting in some security problems. In this paper, the PM-QKD protocol is discussed under the condition of unknown photon number distribution (UPD), and it's confirmed that the security analysis is still reasonable under the condition of unknown photon number distribution, and it's also shown that the key rate generated by PM-QKD protocol based on light source detection is basically consistent with the key rate under ideal light source.