To improve the erosion resistance of the Hydraulic pillar 27SiMn steel in the underground coal mine, a semiconductor fiber coupled laser was adopted to perform multi-pass lap cladding of iron-based alloy powder on the 27SiMn steel substrate, and the transverse of the obtained ferrous alloy study on cladding layer and analysis of macro-profile, microscopic structure, micro hardness, erosion resistance grade and mechanism of erosion. Results show that the dilution rate is the main consideration index. Under the process parameters of 2 000 W laser power, 15 g/min powder feeding rate, 6 mm/s scanning speed and 50% overlap rate, the best dilution rate and cladding layer with good macro morphology can be obtained. The dendrites grown in the upper part of the cladding layer will have obvious directionality. The erosion resistance level of the cladding layer is improved by 2 levels compared to the base material. The Heavily corroded area is intergranular erosion. Erosion resistance is obviously improved compared to the matrix material. This research has important guiding significance for the hydraulic column repair and strengthening engineering practice.