  Quantum Key Distribution, as a branch of quantum mechanics in cryptography,
can distribute keys between legal communication parties in an unconditionally
secure manner, thus can realize in transmitting confidential information with
unconditional security. We consider a Phase-Matching Quantum Key Distribution
protocol with 3-state systems for the first time, where the phase of the
coherent state is 3,thus we propose three different ways to response to every
successful detection and two parties gain their raw keys by "flip and flip".
The simulation results show that compared with Phase-Matching Quantum Key
Distribution protocol where the phase equals 2, the proposed protocol breaks
the limit of linear key generation rate in a shorter distance, and the longest
practical transmission distance is about 470 $km$, whereas the ones of BB84
protocol is lower than 250 $km$.
