Since the single photon is easy to attenuate and be disturbed, its key generation rate and transmission distance in quantum communication systems are generally limited. In contrast, weak coherent pulse (WCP) and heralded single photon source (HSPS) exhibit higher feasibility than the single photon source in quantum key distributions (QKD). We compare the performances of QKD using these two kinds of photon sources and decoy state method, incorporating data-postprocessing methods including the Lütkenhaus scheme and Gottesman-Lo-Lütkenhaus- Preskill (GLLP) scheme. Simulation results indicate that QKD using HSPS can transmit longer distance than using WCP with lower overall quantum bit error rate (QBER) at the same transmission distance, albeit with relatively low key generation rate.