The invention relates to a garbage gasification combustion furnace of a telescopic fire grate structure and a gasification combustion treatment technology. The garbage gasification combustion furnacecomprises a feed bin, a gasification furnace, the telescopic fire grate structure, a burning furnace, a high temperature resistant fan and a secondary combustion chamber; the upper end of the gasification furnace is provided with a flue gas outlet, the flue gas outlet communicates with the secondary combustion chamber through a pipeline, and the lower end of the gasification furnace is provided with the telescopic fire grate structure; the telescopic fire grate structure conveys garbage in the form of sinusoidal wave motion; the upper end of the burning furnace is provided with a flue gas outlet, the flue gas outlet communicates with the high temperature resistant fan and a drying section of the telescopic fire grate structure through pipelines, and the flue gas outlet of the secondary combustion chamber communicates with the high temperature resistant fan and a gasification section of the telescopic fire grate structure through pipelines. The garbage gasification combustion furnace and the gasification combustion treatment technology have the advantages that continuous feeding can be achieved, the contact area between hot air and the garbage is large, the sufficient heat is provided, and continuous gasification incineration treatment of the garbage is achieved.