A comprehensive analysis is made on the performance of decoy-state quantum key distribution with a heralded pair coherent state photon source from the effectiveness, stability and feasibility. The key generation rate, quantum bit error rate, and optimal signal intensity each as a function of secure transmission distance are simulated and analyzed by the three-intensity decoy-state method based on a heralded pair coherent state photon source with four groups of experimental data. Considering the intensity fluctuation, the stability of this method is simulated and discussed. Furthermore, the feasibility of the simple and easy method that is proposed with a heralded pair coherent state photon source is analyzed. The simulation results show that the key generation rate and secure transmission distance obtained from the decoy-state method with a heralded pair coherent state photon source are better than those obtained from the methods with a weak coherent state source and heralded single photon source. With the same intensity fluctuation, the heralded pair coherent state photon source is less stable than the heralded single photon source, but more robust than the weak coherent state source. However, the advantage in the effectiveness of the heralded single photon source can give rise to the shortage of the stability. Moreover, the two same modes of the heralded single photon source provide the feasibility to design a simple and easy passive decoy-state method.