The invention discloses an ecological composting device for organic garbage, which is characterized by comprising a percolate collecting tank and at least one composting bin, wherein each composting bin is respectively provided with a feed door and a discharge door in a sealing mode; the top of each composting bin is provided with a solar water heater; a heating unit is arranged in each composting bin; a water outlet of the solar water heater is communicated with a water inlet of the heating unit; a water outlet of the heating unit is communicated with a water inlet of the solar water heater;each composting bin is provided with a slope bin bottom; the lowest end of the bin bottom of each composting bin is communicated with the percolate collecting tank; the tank bottom of the percolate collecting tank is a slope; and the lowest end of the percolate collecting tank is connected with a fermenting tank. The ecological composting device has the advantages of improving the composting temperature, creating a microenvironment favorable for microbe activity, and quickening the fermentation and degradation of the organic garbage; moreover, the solar water heater provides hot water for theheating unit, the water is recycled, the energy consumption is greatly reduced and the environment is protected.