The new material “black silicon” formed by arrays of sharp conical spikes on the silicon surface is fabricated under the cumulative ultra-short laser pulses irradiation in different ambient atmospheres. The physical mechanisms of conical spikes evolutions impacting silicon surface under picosecond (ps) and femtosecond (fs) laser irradiations are different. The formation of spikes arrays depends on the pulse duration and ambient atmosphere. Especially, in SF6 ambient atmosphere, silicon surface micro-structuring evolutions under ps and fs laser irradiations are analyzed in detail. Under the ps laser irradiation, silicon surface is melted before the spike arrays formed; while under the fs laser irradiation, the formation of spike array does not go through the liquid phase. The preliminary experiment shows that the infrared radiation absorptance is more than 80% at the wavelength range of 1.5～16 μm.