The utility model discloses an improved thermostatic heating oven. The heating oven comprises two communicated cylinder body including a cylinder body A and a cylinder body B. The upper end faces of the cylinder body A and the cylinder body B are flush. The length of the cylinder body B is shorter than the length of the cylinder body A. A reactor, a thermocouple and a plurality of electrical heating rods are arranged in the cylinder body A. A blender is arranged in the cylinder body B. A heating coiling pipe is arranged below paddle blades of the blender. The improved thermostatic heating oven has the advantages that isothermal regions of the heating oven are longer than the isothermal regions of an electric heating oven with the same length of the heating oven and temperature differences of constant temperature areas are small. The improved thermostatic heating oven is simple in structure, uniform in reaction bed layer temperature, fast in ramp rate, and satisfied in reaction operation conditions. The improved thermostatic heating oven is adaptable for catalysts to conduct a rapid evaluation.