The invention relates to industrial by-product gypsum calcining equipment, which comprises a sting-out furnace, a kiln head, a roller, a feed hopper, an anhydrous gypsum discharge hole, a semi-hydrated gypsum discharge hole, a power transmission unit and a waste elevator. According to the invention, a temperature sensor is arranged at the discharge hole of a roller of an existing gypsum drying calcinator, and the discharge hole is also provided with a reversing valve and a discharge pipe. The temperature sensor detects the temperature of a material discharged out of the discharge hole of the roller. When the temperature in the roller is lower than the temperature of qualified gypsum, the temperature sensor controls the reversing valve for reversing, and unqualified gypsum products are conveyed into a waste gypsum storage tank. The waste elevator lifts and conveys unqualified gypsum into the feed hopper of the gypsum drying calcinatory, and then the unqualified gypsum is once again calcined and dried. Therefore, output of unqualified gypsum is reduced, output of qualified gypsum is raised, and raw materials and energy are saved.