Single pass316L alloy powder cladding with different thicknesshas been carried on surface of 27 SiMn 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) and 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, while the surface microhardness of the cladding layer decreases, the corrosion potential and polarization resistance rate increase and the corrosion current density decreases; Compared to 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 are the largest, and the values are 0.053 V and 22.881Ω?cm2,respectively, while the corrosion current density of 1.018 mA?cm–2 is the smallest. It is concluded that the corrosion resistance of 1.0mm thick cladding layer is the best.