By using femtosecond laser direct writing platform, the interaction between femtosecond and semiconductor silicon material are studied. The formation of microstructure on silicon under fixed dot irradiation and scan with femtosecond laser pulse at different laser power and pulses is described. Scanning electron microscopy is used for observing the morphologies of the surface microstructure. It is experimentally demonstrated that the period and morphology of fabricated microstructures is effected by the laser power and pulse number. The orientation of the period stripe is effected by the polarization direction of the incident femtosecond laser. We can control the period stripe orientation by adjusting the polarization direction of the incident laser. Large area of microstructures can be induced on the surface of material by scanning. According to the experimental results, the effect of pulse number on period is analysed . The results provide a reference to the silicon surface microstructures processing.