Abstract: The phase matching protocol is a recent proposed quantum key distribution protocol that breaks the secret key capacity. Its security has been certified by theory and practice. For there is no ideal single photon source in practice, a two-decoy-states phase matching quantum key distribution method is proposed with a weak coherent state source. In this method, the parameters are estimated more easily for only two decoy states (vacuum+weak decoy state) should be taken into consideration that are necessary to solve the final key rate. Then we analyze the performance of the proposed method with fiber channel both in ideal and statistical fluctuation respectively. The simulation results show that the proposed method can break the secure key capacity and has higher key rate and longer max transmission distance than the BB84 (the protocol proposed by Bennett and Brassard in 1984) and measurement device independent protocols under the condition of the same number of decoy state. The proposed method approaches the existing three-decoy-states method in key rate and max transmission distance and breaks the secret key capacity. Taking the statistical fluctuation into consideration, the proposed method will have higher key rate and longer max transmission distance when the data size is less than 10¹⁴.