Quantum key generation rate of decoy state quantum key distribution(QKD) with a heralded single-photon source(HSPS) is deduced.Relationship between quantum key generation rate and detection efficiency of sender is discussed.Optimal intensities and key generation rate of decoy state QKD with a weak coherent pulse(WCP) and an HSPS are analyzed.It shows that key generation rate increases with increase of detection efficiency of sender and its security distance is the same as with a perfect single photon source.Decoy state QKD increases security distance and key rate of QKD.Due to less dark counts QKD with HSPS works longer distance than WCP.