Mode locked fiber laser has the properties of high peakpower and narrow pulsewidth, and can be effectively applied in highaccurate remote ranging and information transmission. In the paper, a method of realizing dualpulsetrain modelocked laser in an allpolarizationmaintaining Erdoped fiber cavity based on graphene saturable absorber is reported. Based on multilayer graphene saturable absorber mirror, stable modelocked fiber laser can be obtained, and cavity loss can be operated by modulating an attenuator in the cavity. By adjusting the gain and loss of laser signal at different wavelength, dualpulsetrain laser centered at 1 531 nm and 1 557 nm can be realized, repetition frequency 57 MHz and extinction ratio of output laser can be up to 19 dB.