NOVELTY - The system has top portion that is linked with crushing drying tank (2) and combustion ash collecting tank (6) is located below combustion furnace (4) such that burned waste is directly fallen into tank (6). A bottom portion of tank (6) is provided with discharging pipe (7) penetrates from opening at bottom portion of cylindrical structure. A methane combustion-supporting conveyor pipe (5) is linked with furnace to provide combustion-supporting methane, while exhaust pipe (8) is connected below furnace and outlet of pipe is located at bottom portion of tank (2).    USE - Harmless processing system for domestic garbage.    ADVANTAGE - The garbage incineration system, a garbage decomposition system and a garbage decomposition liquid ecological system are mutually functioned to implement combustion the garbage without smoke and decomposing the garbage without pollution. The decomposition liquid can be used for growing the plants in building roofs, balconies and public green space, so that the indoor temperature and outdoor light pollution can be reduced and the nutrition content of the domestic sewage can be reduced.    DETAILED DESCRIPTION - A combustion drying device is cylindrical structure with opening located on lower portion and top portion is connected with crushing drying tank (2). The tank (2) is located below flammable garbage storing tank (1) so as to crush garbage. Exhaust pipes (9) are located below combustion drying device and bottom layer of tank (2) is provided with layer of net structure which is convenient for gas to enter and exit. The combustion drying device is cylindrical structure with opening on lower portion and top portion is connected with tank (2). A cylindrical outer wall of combustion drying device has preheating mixing tank (3), a methane combustion-supporting conveyor pipe (5), a combustion furnace (4) and combustion ash collecting tank (6). The tank (3) is located above furnace. A bottom potion of tank (3) is funnel-shaped to enter the objects into furnace. A periphery of tank (3) is provided with net structure which is convenient for gas to enter and exit.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the harmless processing system.    Flammable garbage storing tank (1)    Crushing drying tank (2)    Preheating mixing tank (3)    Combustion furnace (4)    Methane combustion-supporting conveyor pipe (5)    Combustion ash collecting tank (6)    Discharging pipe (7)    Exhaust pipes (8,9)