Based on the model of quantum key distribution (QKD) system with a heralded single photon source (HSPS), three typical BB84-decoy-state methods are introduced including active decoy-state protocol, passive decoy-state protocol and the protocol combining active and passive decoy-state idea. The performance and implementation difficulty of the three decoy-state methods are analyzed with numerical simulation. The results show that the key generation rate of BB84 decoy-state protocol is increased by the passive decoy idea. Passive decoy-state method proposed by Adachi, Yamamoto, Koashi and Imoto (AYKI) is easy to implement and speedy to distribute keys because there is no need to prepare decoy states actively. Furthermore, the performance of the AYKI protocol is close to that of the infinite decoy-state protocol. The performance of the method combining active and passive decoy-state idea is better than that of AYKI protocol, but there is not much room left for improvement after the AYKI protocol is implemented.