The invention discloses a fluidized-bed reactor for landfill leachate aerobic and anaerobic cycle treatment. The fluidized-bed reactor comprises a reactor inner cylinder (8), a reactor outer cylinder (9) and a three-phase separator (10), wherein the reactor inner cylinder (8) is positioned at the lower end of the fluidized-bed reactor, the upper end of the reactor inner cylinder (8) is connected with a cone (11), the reactor outer cylinder (9) is composed of the peripheral space of the lower end reactor inner cylinder (8) and the cone (11) at the upper end, both the upper end and the lower end of the reactor outer cylinder (9) are communicated with the reactor inner cylinder (8). With the reactor, after entering the reactor inner cylinder, garbage waste water firstly sequentially enters an aerobic area, an anaerobic area and an anaerobic area, passes through a process similar to an inverted A2O technique, thereby achieving the effects of highly effective COD removal and nitrogen removal by simultaneous nitrification and denitrification, realizing advantages of cycle complementation in aerobic and anaerobic process, greatly simplifying technical procedures, saving covering area andinvestment cost and having low operation cost.