Decoy state has recently been proved as a useful method for substantially improving the performance of quantum key distribution (QKD). Considering the imperfect extinction ratio and the spontaneous emission of the practical Laser, vacuum states are not prepared easily. So in this paper, the optimal situation of the decoy state protocol applied to the QKD system with heralded single photon source (HSPS) is complemented and extended. The two weak decoy state protocol and the one decoy state protocol are proposed. At last, the theory of “dual detectors" is combined with the QKD system with HSPS. In the simulation, the secure distance is up to 2215 km, which is approximately 50 km more than that of the on-off detectors.