The invention relates to laser-cladding cobalt-based alloy powder and a method for preparing the same and is characterized in that the cobalt-based alloy powder comprises, by mass, 0.1% to 0.4% of C, 3.5% to 5.5% of Si, 1.5% to 3% of B, 1.6% to 2.5 % of Mn, 1.0% to 3.0% of Cr, 0.5% to 2% of W, 0.5% to 3% of Ni, 0.1% to 0.4% of Nb, less than 15% of Fe, 0.2% to 0.3% of La2O3, 0.4% to 0.5% of rare earth Y, and the balance Co and inevitable impurity elements. A technological process for manufacturing the laser-cladding cobalt-based alloy powder includes compounding, smelting, atomizing, drying and screening. The laser-cladding cobalt-based alloy powder is corrosion resistant and high in rigidity, and a laser-cladding layer after treatment has the advantages of being free of cracks, air holes and impurities, compact in organization, fine in crystalline grain and the like. The laser-cladding cobalt-based alloy powder and the method for preparing the same have the advantages that a laser-cladding alloy layer of a large area and thickness and free of cracks can be obtained under the condition that preheating and subsequent heat treatment are not needed, the cladding layer is high in strength, rigidity and abrasion resistance, the plastic toughness is good, the cost is low and the like.