In order to improve the corrosion resistance of metal materials for sea pipeline, Ni coating was prepared on the surface of 30CrMnSi low alloy steel by medium and low pressure cold spraying process. The effects of spraying process parameters (spraying gas pressure and temperature) on the microstructure, electrochemical properties and salt water resistance of the coatings were studied by digital camera, scanning electron microscope and electrochemical workstation. The results showed that the thickness of the cold sprayed Ni coating prepared by CS1 (0.8 MPa-150 ℃), CS2 (1.0 MPa-200 ℃), CS3 (1.5 MPa- 200 ℃) and CS4 (1.7 MPa-250 ℃) increased from 155 μm to 265 μm, the porosity of the coating decreased from 3.5% to 0.9%, and the self-corrosion potential (Ecorr) increased from ?0.623 V to ?0.328 V (vs. SCE). The corrosion current density (Jcorr) decreased from 4.3×10?5 A/cm2 to 4.4×10?6 A/cm2. The cold sprayed Ni coating under four process conditions still had corrosion protection effect on the substrate after 1 000 h artificial seawater immersion test. The degradation mechanism of cold sprayed Ni coating in artificial seawater environment is derived from the loose properties and internal pores of the coating surface. At the initial stage of immersion, chloride ions rapidly penetrate into the interior of the coating and form soluble chlorides, forming relatively closed corrosion pits. With the prolongation of immersion time, the pores inside the coating are gradually filled with these products, and the corrosion surface layer becomes more stable and dense, and a protective layer is gradually formed, thus blocking the further replenishment of fresh chloride ions. In the later stage of immersion, the significant difference in electrochemical conditions inside and outside the blocking area accelerates the corrosion process of the metal in the corrosion pit. The volume expansion of the corrosion products accumulates on the surface or the cracks under the action of stress, the channel of chloride ions opens again, and the corrosion surface gradually falls off. By increasing the spraying pressure and spraying temperature, the density and bonding strength of the cold sprayed Ni coating can be effectively improved, and the corrosion propagation process of the coating in the salt water environment can be effectively inhibited. At present, the nickel coating prepared by medium and low pressure portable cold spraying system in China is still in the laboratory stage, and its application in industry is rarely reported. In this paper, the effects of medium and low pressure cold spraying parameters on the microstructure and properties of Ni coating on the surface of alloy steel are carried out to meet the requirements of marine equipment for the performance of cold sprayed Ni coating. The corrosion failure data of cold sprayed Ni-based coatings under different process conditions in the artificial environment are accumulated, and the advantages of flexible medium and low pressure portable cold spraying systems, small spray gun size, relatively low equipment and processing cost are fully utilized. It provides theoretical support for the preparation of corrosion protection coating in confined space and on-site repair of damaged parts.