To meet the application requirements of photoelectric countermeasures， hyperspectral lidar， and optical coherence tomography， among others， nIR supercontinuum output with high flatness must be obtained and the effect the backwardness of light enhancement on the stability of a laser system during nonlinear amplification should be prevented. The experiment employed a picosecond pulse laser seed source with nonlinear frequency component， and the laser was built with a fiber nonlinear amplifier to produce supercontinuum output directly， solving the problem of returning light effectively. Using the nonlinear fiber amplifier to generate supercontinuum is an effective way to realize a high-power supercontinuum light source. The method combines the laser gain amplification process with the nonlinear supercontinuum broadening process， achieving simple and compact system structure. The SESAM passive mode-locked picosecond pulse was used to achieve a first-order Stokes frequency broadening through two-stage amplification. Finally， a third-stage nonlinear fiber amplifier was used to realize a near-infrared supercontinuum output power of 56 W at a wavelength range of 950~1650 nm， flatness of 10 dB （excluding pump light）， and opto-optical conversion efficiency of 48%.