The modulation instability generated by 2 μm dissipative soliton fiber laser under high peak power is studied. The effect of nonlinear effects on the optical pulse characteristics is analyzed by calculating the dynamic process of the dissipative soliton modelocked model. By introducing the dispersion compensation fiber into the annular cavity and adding the radius of the mode field, the net positive dispersion is enlarged and the selfphase modulation effect is reduce in the cavity. Aiming at the larger linear chirp pulse output, 46.83 m large mode area fibers is taken to compress out of cavity. Finally the stable pulse output with peak power of 17.1 kW and pulse width of 169 fs is obtained.