Abstract: In order to improve the erosion resistance of the tools in the process of oil and gas production under the conditions of high temperature, sand, etc., the laser cladding was employed to prepare the Co-based metal-ceramic composite coating on 1Cr18Ni9Ti austenitic stainless steel with Co metal powder+10%WC+3%Al. The erosion behavior of the deposited layer was investigated by erosion test. The results show that the deposited layer on the tool surface is dense and uniform, which is the metallurgical bonding with the substrate. The deposited layer is generally divided into three zones: one zone where the plane crystal and cellular crystal are perpendicular to the layer, one zone where the dendrite crystal in multi-directions transfers to the middle of the molten pool, and the other zone where the tiny dendrite grains are parallel to the laser scanning direction near the surface. The cobalt-based composite coating surface is smooth with only a few pits and furrows, which can improve the erosion resistance and service life of tools used in oil and gas wells.