NOVELTY - Sludge composting device comprises solar heater, reactor, water circulation pipeline, and blast blower. The solar heater comprises heat collecting pipe, thermal insulation box and bracket. The bracket is provided with the thermal insulation box. The side of the bracket is provided with multiple heat collecting tubes in parallel. The upper end of the multiple heat collecting tubes are respectively connected to the thermal insulation box in which top is provided with vent valve. The reactor comprises container and partition plate.    USE - As sludge composting device.    ADVANTAGE - The device has rapid starting time and composting time, facilitates control of temperature of compost portion, so as to rapidly decompose compost portion, and improves composting efficiency. The composting temperature can be raised rapidly through action of sunlight energy, thus providing proper growth temperature for microorganisms, maintaining microorganisms active, sufficiently decomposing organic matter in sludge and effectively improving transformation rate of saltpeter and nitrogen in sludge. The device solves problems of severe nitrogen loss, long composting time and easy influence by ambient temperature for existing composting systems.    DETAILED DESCRIPTION - Sludge composting device comprises solar heater, reactor, water circulation pipeline, and blast blower. The solar heater comprises heat collecting pipe, thermal insulation box and bracket. The bracket is provided with the thermal insulation box. The side of the bracket is provided with multiple heat collecting tubes in parallel. The upper end of the multiple heat collecting tubes are respectively connected to the thermal insulation box in which top is provided with vent valve. The reactor comprises container and partition plate. The partition plate is located on the lower portion of the container which is separated into upper and lowers two layers. The partition plate is provided with uniformly distributed through hole. The lower layer side wall of the container is opened with a vent. The water circulation pipeline comprises coil pipe, water inlet pipe, water outlet pipe and circulating pump. The coil pipe is provided with lower layer of the container of the reactor. One end of the coil pipe is connected with the upper part of the thermal insulation box through the circulating pump and the second switch valve. The other end of the third switch valve is connected with the outer water source. The blast blower comprises air pump, time relay, fourth switching valve and rotor flow meter. The power source line of the air pump is connected with outer power source through the time relay. The air outlet of the air pump is connected with the inlet of the rotor flow meter through the fourth switching valve. The outlet of the rotor flow meter is connected with the vent on the lower part of the container.