The invention discloses a welding method of a nickel-base alloy steel pipeline. A groove of a pipeline to be welded is treated, the angle of the groove of the pipeline to be welded is 70-75 degrees, the poor mobility of material liquid metal is avoided, the groove of the pipeline to be welded and the outer surface of the pipeline to be welded are polished and cleared, the situation that an oxidization layer exists on a weld opening is prevented, then after the pipeline is located and fixed, argon is adopted for protecting the groove of the pipeline to be welded, layering welding is adopted, and the situation that due to the improper welding temperature, as a result, metal grain of weld seams is thick and large, and the mechanical performance and corrosion resisting performance of the weldseams are lowered. According to the method, the scheme is reasonable, the data is reliable and explicit, the problem of 800 H welding quality can be effectively solved, the welding quality is improved, a left gas blocking baffle, a right gas blocking baffle and the inner wall of the pipeline to be welded are utilized for forming a sealing structure, then multiple gas output holes in a gas conveying pipe are utilized for inflating argon into the weld opening, the stable argon environment atmosphere is provided for welding, the device is simple in structure, and stability of the welding environment is ensured.