With controlling the femtosecond (fs) laser polarization and scanning direction, the regular distribution of composite micro/nano structures was induced on the surfaces of silicon and stainless steel by Orthogonal Line Scanning Processing (OLSP). The influence of laser fluence on the micro/nano structures was studied. The experimental results show that two-dimensional (2D) composite structures nested with periodic ripples and nanoholes are induced on the silicon wafer surface, however, nanorod arrays at the edge of scanning area are induced on the stainless steel surface when the laser fluence is close to the material ablation threshold. The analysis indicates that the nanorod arrays are formed by the fracture of periodic ripples. Moreover, when laser fluence is higher than the ablation threshold, the regular distribution of micro hole structures is induced both on the surfaces of silicon and stainless steel. The experimental results demonstrate that the micro/nano structures induced by the first line scanning enhances its laser absorption and promotes the coupling between the incident fs laser and the surface plasma wave, so that the ablation of the second scanning is enhanced and the later structures induced by the second scanning becomes a dominating. In conclusion, the OLSP provides a new approach for fabrication of surface micro/nano structures.