An all-polarization-maintaining erbium-doped fiber laser mode-locked by graphene saturable absorber mirror was reported. The laser with monolayer and ten-layer graphene as saturable absorbers devices avoided the influence of environment on the intracavity polarization and generates high stability, high degree of polarization and self starting mode-locked pulse output with pulse width of 697 fs and 502 fs. Compared to single layer graphene, the ten layers graphene can obtain shorter pulse width, higher peak power and better mode locking effect. While the pump power increases, a two harmonic mode-locked pulse with 62.94 MHz repetition frequency can be generated. The mechanism of harmonic mode locking was analyzed by nonlinear Schrodinger equation. The mode-locking laser cavity based on the reflection mirror was expected to be the excellent single polarization femtosecond fiber laser source which can be switched between the fundamental frequency and the two harmonic.