In order to realize a highly stable and tunable laser output, an Er3+-doped fiber laser based on Mach-Zehnder filter structure and grating array made by femtosecond laser was proposed, and an optical delay line(ODL) was set into one interference arm to tune the interference interval flexibly. In the designed configuration, one 976 nm laser diode (LD) was used for pumping; an Er3+-doped fiber (EDF) of 6 m length was selected as the gain medium; The grating array will selete the femtosecond light reflection loop cavity specific wavelength oscillation form; the M-Z structure, which was used as comb filter, was adopted to select the wavelength reflected by the grating array; Tuning laser output can be realized by adjusting the ODL. In the experiment, when the pump power was 100 mW, a stable and tunable single, dual and triple wavelength output laser was observed. The single wavelength tunable interval was 2 nm within 1 570-1 596 nm, and the side-mode suppression ratios (SMSRs) of all were more than 50 dB.