The invention relates to a microwave sintering furnace, in particular relating to a three-section four-door long-tunnel energy-saving type microwave sintering furnace, which comprises a microwave sintering tunnel furnace, tracks and a kiln car and is characterized in that the appearance of the furnace body is in a long box structure, a base is arranged under the furnace body, two tracks are paved, the side surfaces of the furnace wall are provided with equally spaced gate slots and square sliders, and four lifting type steel doors divide the furnace chamber into a cooling section, a sintering section and a preheating section; a hot gas pumping pipeline is arranged between the cooling section and the preheating section; the top part of the tunnel furnace body is provided with a waveguide port; the kiln car is in a box-combined structure and comprises track wheels, a carframe in a steel square frame type structure, an air inlet and a heat-resisting material layer, the front and rear ends of the kiln car are respectively provided with an auricled door bracket, a connecting piece and a groove, and a kiln car group is formed by connecting 1 to 5 kiln cars; and the microwave sintering furnace also comprises three groups of servo motors controlled synchronously and driven systems. Compared with the traditional kiln furnace, the microwave sintering furnace has high heating speed, saves power by 40-50%, shortens time by 1.5h, achieves the aims of saving energy and reducing consumption and improves economic benefit.