The invention is a fluid bed gasification and combustion processing method for urban garbage. The hearth of a fluid bed garbage furnace (4) is composed of two parts of a low temperature gasification area and a high temperature combustion area, additives (f) such as limestone, kaolin, etc. are added to the garbage furnace (4); acid gases such as chlorine, sulfur, nitrogen, etc. are removed in the furnace; and the generation of dioxin is controlled in the furnace. A water cooling spiral slag cooler (5) and a vibration sieve (6) can be utilized to efficiently reduce heat loss of slag and recycle bed materials. The whole system requires no addition of auxiliary fuel, and has the characteristics of safe reliability, no odor emission, low investment and operating cost, less secondary pollutant discharge, high power generation efficiency, etc.