The invention relates to an efficient welding device with energy conservation and environmental protection, comprising a propane synergistic agent synthesizer (including electrical appliances) and a quick dicyclic welding torch and a quick dicyclic cutting nozzle matched with the propane synergistic agent synthesizer, wherein the propane synergistic agent synthesizer is formed by combining a synthesizer body 1, an air agent synthesizing tank 2, a synergistic agent feed pipeline 3, a propane feed pipeline 4 and a fuel gas output pipeline 5. During real working, synthesized fuel gas is sprayed out from an inner ring of the quick dicyclic cutting nozzle and is mixed with oxygen to combust to form a primary combustion motive power field, and outer ring fuel gas acted by the obliquity action of the cutting nozzle is sprayed out and is caused to cross the primary combustion motive power field to combust, thereby forming a secondary high-temperature concentrated combustion motive power field; and the flame temperature reaches up to 3410 DEG C, the cutting speed and the cutting quality are greatly increased and improved, the cutting yield is as high as 97 percent, and the cutting oxygen is saved by 35 percent; and compared with acetylene, fuel gas is saved by 30 percent, and the welding seam is reduced to 2 to 2.5mm from the original 8 to 10 mm. The device is ideal equipment for steelrolling lines of continuous casting workshops of steel mills and billet steel flame cutting and remodeling, has favorable application value, and can be widely applied to the industries, such as metallurgy, shipbuilding, petroleum, chemical industry, metallic structure, etc.