Quantum key distribution (QKD) allows two remote parties to generate a theoretically secure key. However, the imperfections of the light source and measuring device often exist in practice, which causes different attacks on the quantum key distribution system. To eliminate these attacks, the researchers proposed a twin field QKD protocol. The protocol encodes the key information in the phase of the photons so that the photons are easily transmitted and maintained, which not only extends the transmission distance, but also solves the safety problem of the measuring device. Inspired by this, a new B92 protocol based on phase encoding is proposed. Compared with the original B92 protocol, the new protocol not only eliminates the attack of the detector, but also imporves the key rate. There is no need for a base step in the post-processing process in this new protocol, and only two non-orthogonal quantum states are used by both communicating parties, and moreover, it is easy to implement in practice.