Starting from the extended nonlinear Schrdinger equation in which the quintic nonlinearity effect is included, the evolution and splitting process of continuous optical wave which is amplitude perturbed by the sine optical wave into ultra-short optical pulse trains in optical fibers is numerically simulated by adopting the split-step Fourier algorithm. The effects of the quintic nonlinearity and the modulation period of the sine optical wave on the generation and evolution of ultra-short optical pulse trains and the corresponding spectra are investigated. The results show that, in comparison with the case of cubic nonlinearity only, the positive quintic nonlinearity can shorten the optimal fiber length required to form the pulse trains and make every pulse shorter in width and higher in peak power, while the negative quintic nonlinearity takes the opposite. The sine modulation period may influence the pulse repetition rate and the optimal fiber length. With the increase of the propagation distance, every single pulse may split into two and even three sub-pulses. Moreover, some small pulses with weak peak powers may appear among the main pulses. In terms of the frequency spectra, the positive (negative) quintic nonlinearity can make the number of frequency components increase (decrease) and the spectral width wide (narrow). Depending on whether the main pulses split and the small pulses exist or not, the spectra take on different shapes.