In-situ observation on the self designed thermal spraying meta l coating for long time protection to the jackets of Center No.2 platform in the Sheng li Oil Field in Chengdao showed that the spraying aluminum coating had good corrosion resistant effect on the marine platform. The base was protected from corrosion even when the organic pain ting on surface had fallen off. Mere aluminum coating could not provide good electrochemical protection to the base near the water line. The coating's protective effect in the marine atmosphere zone did not decrease even when the organic paint on the surface was scuffed up or had dropped. The organic paint used to seal the spraying metal coating must have high cohesive affinity and penetration. The two years experiment in the open sea showed that the most economic and effective protective method is to spray zinc coating first, then spray aluminum coating and then to seal the metal coatings with alloprene paint.