The invention discloses a spiral automated welding rolling machine for tanks. The spiral automated welding rolling machine for the tanks comprises a steel plate decoiling device, a steel plate leveling device, a steel plate edge cutting device, a groove machining device, a conveying device and a cylinder rolling device which are sequentially arranged and mounted, and a welding mechanical arm is arranged on one side of the cylinder rolling device. When in use, firstly the steel plate decoiling device decoils a roller-shaped steel plate, the steel plate leveling device levels the steel plate, the steel plate edge cutting device cuts the steel plate, the groove machining device machines the steel plate, the conveying device conveys the steel plate into the cylinder rolling device, and finally, the cylinder rolling device and the welding mechanical arm finish welding and cutting of internal and external gaps of a tank body. The spiral automated welding rolling machine for the tanks implement integration of six steps of decoiling, leveling, edge cutting, rolling, welding and cutting in a tank body manufacturing process, so that the production efficiency is improved, the production area and labors in the production process are reduced, and an oil tank manufacturing process is changed from multiple-operation and multiple-labor coordinative production into automated production.