The invention relates to the technical field of gypsum decomposition and provides a method for decomposing gypsum through synergistic fluidization. The method comprises the steps of 1, uniformly mixing gypsum granulated raw materials with fluidizing agent particles, adding the gypsum granulated raw materials and the fluidizing agent particles into a bed body, and raising the temperature of the bed body to the set temperature; 2, introducing a gas mixture of a gas phase reducing agent and fluidization gas through a gas inlet pipe; 3, under the action of wind power of the gas mixture, making mixed particles of gypsum and a fluidizing agent enter and suspend in an isolator, and making the gas phase reducing agent be in contact with and react with the gypsum particles, so that calcium oxide particles, calcium sulphide particles and sulfur dioxide gas are obtained; 4, carrying the calcium oxide particles, the calcium sulphide particles and a small amount of gypsum particles obtained after the reaction out of the bed body with gas, while making the fluidizing agent and gypsum particles which are not involved into the reaction fall back to the bottom of the bed body through a gap between the isolator and the side wall of the bed body for reutilization; 5, introducing inert gas through a secondary air inlet structure. By means of the method, the space-time yield of sulfur dioxide is high, decomposition efficiency is high, and production cost is low.