A system for treating high-salt and high-organic-matter wastewater and recovering energy, the system comprising a cold wall reactor (6), s multi-stage cyclone separation device (16, 19, 25), a waste feeding system, an oxidant feeding system and a fuel feeding system. The cold wall reactor (6) is provided with cooling medium inlets (6011, 6012, 606, 608) at the top and bottom thereof and cooling medium outlets (603, 609) at the sides thereof, and an inner pipe (6001), a middle pipe (6002) and an outer pipe (6003) are provided at the middle of the top thereof in sequence; a reaction fluid outlet (607) is formed at the bottom of a double-layer shell; the reaction fluid outlet (607) is connected to a buffer tank (10), and a top outlet of the buffer tank (10) is connected to the multi-stage cyclone separation device; the multi-stage cyclone separation device is used for recovering steam in a reaction product in the cold wall reactor (6) and crystallizing inorganic salts; the waste feeding system is connected to a waste inlet (6010) on the outer pipe (6003); the oxidant feeding system is connected to an oxidant inlet (602) on the middle pipe (6002); and the fuel feeding system is connected to a fuel inlet (601) on the inner pipe (6001). Also disclosed is a method for treating high-salt and high-organic-matter wastewater and recovering energy.