The invention relates to an automatic de-molding device for angular formworks. The automatic de-molding device comprises the angular formworks, boosting sheets, hydraulic devices and a control system,wherein the angular formworks are combined angular formworks; the angular formworks form an angular formwork production line; free movement is realized through a hydraulic system and bottom rails; the boosting sheets are of any shape, are fitted to the angular formworks under a withdrawal state, and push the angular formworks to complete de-molding; the hydraulic devices are mounted in the angular formworks; the four hydraulic devices at each side of each angular formwork push the boosting sheets, so that the angular formworks are uniformly stressed in a de-molding process; and the control system controls boosting and withdrawing of the hydraulic devices, the hydraulic devices synchronously act under an automatic condition, and the hydraulic devices in the angular formworks can be controlled one by one under a manual condition. The automatic de-molding device improves production efficiency while guaranteeing quality, so that the yield of the angular formworks is increased, de-moldingautomation of the angular formworks is realized, requirements on production efficiency of the angular formworks are met, and development of an assembly type housing plant is promoted.