The invention discloses a contra-rotating outer framework water-air dual-purpose engine. The engine mainly structurally comprises a supporting frame, an oil electric pipeline, a front 
thrust bearing, a 
peripheral bearing, a 
radome, an inner duct, an outer duct, a 
gas compressor, a ring-shaped 
combustion chamber, a worm wheel, a rear 
thrust bearing, a convergent 
tail spray tube, a central duct, an inner rotor, an outer rotor, a blade tongue-and-groove, a fan, an engine cover, a 
power transmission circuit, a conductive slide ring, an oil conveying pipeline, a convergent channel, a rotary joint, a 
metal fuel cavity, a 
metal-water reaction 
combustion chamber and a fan 
stator blade. The 
gas compressor and the worm wheel of the engine are not provided with a 
stator blade, and an outer frame rotor and an inner rotor are in 
counter rotating in an air working state, so that the 
gas compressor and the worm wheel can realize 
counter rotating, the 
absolute rotation speed of the rotor is lowered when the 
engine efficiency is improved, the axial dimension of the engine is shortened and the structure weight is reduced. When the engine works in water, the ring-shaped 
combustion chamber does not work, the inner and outer rotors are static, and power is produced by the 
metal-water reaction 
combustion chamber, so that water-spraying propulsion is realized.