In this paper, propagation of Gaussian optical pulses in the nonlinear gain medium is ana-lyzed theoretically. The mechanism of Gaussian optical pulses compression, broadening and optical soliton formation is also explained. Gaussian optical pulses with different parameters propagating in nonlinear gain medium are simulated with computer. The change of pulse width during the propagation is obtained. The results indicate that it is possible for the ini-tial Gaussian optical pulses with different peak power to form different order solitons in the medium, nevertheless, their propagation distance is limited due to the existence of gain.