The invention discloses nickel base alloy powder used for a coating. The nickel base alloy powder used for the coating comprises the following raw materials including, by weight, 1%-5% of magnesium, 35%-45% of cobalt, 7%-10% of chromium, 2%-5% of molybdenum, 2%-5% of boron, 3%-5% of silicon and 40%-50% of nickel. A preparing method of the nickel base alloy powder used for the coating includes thefollowing steps that the technological processes for preparing the base alloy powder include burdening, centrifuging, atomizing, screening, grinding, mixing, drying and screening; and in the burdeningprocess, hydrous magnesium sulfate, cobalt nitrate hexahydrate, chromic nitrate nonahydrate, erbium nitrate pentahydrate, boron powder, silicon dioxide and nickel nitrate hexahydrate with the corresponding proportions are taken, water is added for mixing, stirring is conducted for 2 min to 7 min through a stirring machine, and a mixture is obtained. By means of the nickel base alloy powder usedfor the coating and the preparing method of the nickel base alloy powder used for the coating, the anti-crack performance, the forming property, the technology stability and the component uniformity of the alloy powder in a laser cladding layer are fundamentally achieved and improved, and the requirements of urban pipelines and equipment for the comprehensive performance such as heat resistance, corrosion resistance, wear resistance and high strength of the cladding layer are met.