The evolution of the solitons from 10 GHz optical pulses with frequency chirp is experimentally investigated in standard single-mode fiber with different lengths by use of the pulse analyzer with the secondharmonic generation frequencyresolved optical gating. It is found that the pulses can evolve into the fundamental soliton when input power is higher than its the theoretical value. The temporal width, frequency chirp and timebandwidth product of the pulses which have propagated over 3.5 dispersion length in the fiber decrease with increase of input power. The pulses almost remain unchanged in width, but vary with the propagation distance in temporal shape, frequency chirp and timebandwidth product in the sequent propagation. The higher input power is, the narrower temporal width of the formed soliton is. When input power is lower than the predicted value from the soliton theory, the pulses cannot evolve into the fundamental soliton,the temporal width of output pulses increases and the frequency chirp decreases with increase of propagation distance.