Based on a theoretical model of a 2-μm thulium-doped mode-locked fiber laser and nonlinear Schr?dinger equation (NLSE), this study analyzed the evolution conditions of self-similar pulses in the laser. The peak power output of the self-similar pulse was approximately 22.66 W. Further, the effects of parameters, such as net dispersion, length of dispersion-compensation fiber, and gain coefficient on self-similar pulses were simultaneously studied. The results show that increasing the net dispersion in the cavity and the length of the dispersion-compensation fiber increases the pulse width and decreases the energy of the single pulse. Moreover, increasing the small-signal gain coefficient increases both the pulse width and energy of the single pulse.