The influence of third-order dispersion on fundamental optical soliton propagation in monomode fibers is studied by the numerical solution of the nonlinear Schrodinger equation.The results show that due to the effect of third-order dispersion

the fundamental soliton pulses are broadened in the propagation

the peak energy gradually decreased

the pulse shape distorted

the center of the pulses shifted sideward and an unsymmetrical trailing oscillatory structure formed.With the additional effect of second order dispersion

the resulted pulse oscillation will be mitigated.In consideration of the nonlinear effect

the peak power decline arising from the dispersion effects is to a certain extent compensated and the generation of unsymmetrical trailing is inhibited.