The invention provides a microwave-fluidization roasting device for treating complex refractory iron ores. The microwave-fluidization roasting device comprises a reaction chamber and a microwave cavity arranged outside the reaction chamber, and a quartz net is arranged in the reaction chamber; a thermocouple is inserted from the top end of the reaction chamber, and a gap is formed between the bottom end and the quartz net; a protective gas inlet and a reducing gas inlet are formed in the bottom end of the reaction chamber, and an exhaust port is formed in the top end of the reaction chamber; and a microwave generation device is assembled outside the microwave cavity. According to the device, the efficient comprehensive utilization of the complicated and difficult-to-select weak magnetic iron ores can be realized, the advantages of fluidization roasting and microwave heating are concentrated, and the defects in existing applications are overcome.