The invention discloses a method for welding and manufacturing weather-resistant suspension bridges with all welded steel structures and stiffening beams. The method has the advantages that the weather-resistant suspension bridges are welded by the aid of diversified welding materials and welding processes which are matched with weather-resistant steel, weld preheating and interpass temperatures are controlled, accordingly, the mechanical properties and the weather resistance of weld joint zones can be assuredly matched with parent metal, and coating-free service requirements of cold regions can be met; the diversified welding processes are used with one another, accordingly, the work efficiency can be greatly improved, and the construction periods can be shortened; measures such as full-cross-section weld joint position arrangement, groove designs, welding sequence control and inter-section port adjustment are adopted, accordingly, the manufacturing and mounting precision of the integral bridges can be guaranteed, and welding deformation can be reduced.