Disclosed is nickel-based powder for low-pressure cold gas dynamic spraying and a preparation method. The nickel-based powder comprises the components of, by mass, 55%-75% of nickel powder and 25%-45%of Al2O3 powder, and the sum of the mass percentages of the components is 100%. The preparation method comprises the steps that (1) the flocculent nickel powder which has the particle size range of 10-40 [mu]m and is prepared through an electrolytic method and the polygonal alpha phase Al2O3 powder are selected; (2) the powder materials are dried; and (3) the powder is weighed out from the powdermaterials according to the proportion and mechanically mixed to be uniform. Thus, the nickel-based powder for low-pressure cold gas dynamic spraying can be obtained through the steps, wherein the order of the step (2) and the step (3) of the steps can be exchanged.