The invention discloses a system for preparing a starch solution for producing a gypsum board. The system comprises a mixing device for mixing raw materials and a feeding device for supplying starch to the mixing device, wherein a diluting device for diluting starch is arranged between the feeding device and the mixing device. According to the system for producing the gypsum board, starch is added in a form of solution instead of dried powder due to addition of the diluting device, strength of the gypsum board is not affected, consumption of the starch is reduced, the cost is saved, and large-scale production is easy to realize. A traditional accessory solution is mostly prepared firstly and then used, the traditional method is broken through by the system, the starch solution is used while being prepared, and accordingly, the system balance is achieved, and manpower and time are saved greatly.