The influence of overlapping rate of focused femtosecond laser spot on colorization of silicon surfaces is investigated. Experimental results indicate that the generation of periodic nanoscale ripple structures induced by femtosecond laser pulses is responsible for the silicon surfaces colorization. In the case of a certain femtosecond laser power, the colorization cannot be realized with too high or too low overlapping rate of focused laser spots.For a special range of laser power, the denser overlapping rate of focused laser spots, the more colors are observed, and the higher colorization efficiency is achieved. In addition, the measurement results of reflection indicate that the refection rate of colorized samples reduces about 50% in the visible light range. The window parameters for silicon surfaces colorization by femtosecond laser are obtained, which paves the way for femtosecond laser semiconductor colorizing technology.