A modified scheme of measurement-device-independent quantum key distribution (MDI-QKD) protocols based on the heralded pair coherent state (HPCS) is proposed, which decreases the error rate caused by the dark count in the long distance quantum key distribution. The simulation results show that, compared with a weak coherent source, the HPCS can reduce the quantitative proportion of vacuum and thus increase the transmission distance. Compared with a heralded single photon source, the HPCS can enhance the quantitative proportion of single-photon pulse and thus increase the secure key generation rate. The impact of the finite key length on the MDI-QKD of the three decoy state based on the HPCS is analyzed.