A multi-layer coiled tube type flash heater comprises an end socket, a cylinder, a coiled tube assembly and a supporting plate. The end socket is detachably connected with the cylinder through a flange. The coiled tube assembly is located in the end socket and the cylinder and fixedly connected with the end socket. The coiled tube assembly is arrayed from bottom to top in a multi-layer mode. Coiled tubes in each layer are arrayed in an S shape in a reciprocation mode, and the pipe diameters of the coiled tubes gradually increase from bottom to top. The multi-layer coiled tube type flash heater is simple in structure, the pipe diameters of the coiled tube assembly gradually increase from bottom to top, and vaporization space is provided for materials; the S-shaped coiled tube type is adopted, and therefore the volume and the area are large, and the heat transfer efficiency is high; a slide way is arranged in the cylinder, and therefore the coiled tube assembly can be conveniently pushed in and pulled out, and convenience is provided for overhauling; the whole coiled tube assembly inclines by a certain degree, and therefore it can be ensured that liquid inside the coiled tubes can be completely discharged, and the multi-layer coiled tube type flash heater is easy to clean and convenient to maintain.