The phenomenon of mutli-soliton pulse is studied in Tm/Ho-codoped fiber laser based on a nonlinear amplified loop mirror as an artificial saturable absorber. By simply adjusting the polarization angle of Polarization Controller (PC), the experiment not only obtained a stable single-soliton pulse, but also observed the pulse sequences of the two-soliton, three-soliton and four-soliton. Increase the pump power under polarization maintaining operation, the evolution of soliton energy quantization is also obtained. The weak birefringence effect in the cavity is important for limiting the gain bandwidth and inducing the generation of multi-soliton. Adjusting the PC is equivalent to changing the gain in the cavity, which is the main reason for the formation of different multiple pulses states. We believe that the results obtained will be helpful in the investigation of multi-soliton pulses dynamics in 2 μm mode-locked fiber lasers.