In order to improve the maximum gain saturation energy of similariton laser, an optimized laser system was designed by replacing single-mode fibers(SMF) with dispersion decreasing fiber (DDF) in similariton laser ac-cording to the advantage of the strong resistance to optical wave breaking while similariton generated in dispersion decreasing fibers. Theoretical analysis and simulation verification were both carried out. The result shows that the maximum gain saturation energy that the modified laser can tolerate is increased by 33.3%. Replacing SMF with DDF for pulse evolution can effectively improve the maximum gain saturation energy of the laser. With the larger gain saturation energy, the output pulse energy of the laser is increased by 109.2%, the pulse peak power increased by 20.6%, the pulse width shortened by 23.1%, and the self-similar evaluation factor decreases from 0.077 to 0.065, resulting in achieving a high-quality similariton with a larger pulse energy, higher peak power, narrower pulse width. This study has certain reference value for obtaining high-power self-similar pulses.