Single pass 316L alloy powder cladding with different thickness has been carried on the surface of 27SiMn hydraulic support column by using YLS-6000 type ytterbium doped fiber laser. The effect of cladding layer thickness on the coating structure， mechanical properties and corrosion resistance was studied by optical microscope （OM），scanning electron microscope（SEM），energy spectrum（EDS） microhardness meter and electrochemical analysis methods.The results show that，with the increase of cladding layer thickness，the cladding layer structure changes from a single columnar crystal to a layer structure including planar crystal，columnar crystal and dendritic crystal，the surface microhardness of the cladding layer decreases，the corrosion potential and polarization resistance rate increase and the corrosion current density decreases；Compared with 0.3 mm and 0.5 mm thick cladding specimens，both the corrosion potential and polarization resistance rate of 1.0 mm thick cladding layer samples show the largest values of 0.053 V and 22.881Ω·cm2，respectively，while the smallest corrosion current density of 1.018 mA·cm-2 occurs. It is concluded that 1.0 mm thick cladding layer exhibits the best corrosion resistance.