A precise casting device for a thin-wall box comprises a die mechanism, a die fixing mechanism, an insulating mechanism, a heating mechanism, a temperature control mechanism, an exhausting mechanism and a cooling mechanism. The die mechanism is provided with an outer die. A core die and a core side die are arranged in the outer die, and a core angle die, the core side die and a core middle die are arranged. Positioning screws are arranged in a pressing die plate and the outer die in the die fixing mechanism. A top pressing plate is arranged at the upper end of an upper die, and a lower supporting plate is arranged at the lower end of a lower die. In the insulating mechanism, insulating layers are arranged between the die mechanism and the pressing die plate, between the die mechanism and the top pressing plate and between the die mechanism and the lower supporting plate. In the heating mechanism, an electric heating pipe hole is formed in the die mechanism; a thermocouple hole is formed in the temperature control mechanism; the exhausting mechanism is provided with an exhaust hole and an upper exhaust pipe; in the cooling mechanism, a cooling channel is formed in the outer die; the die mechanism is made of graphite materials; and during using, coatings are not needed, the manufacturing precision is high, the procedure is high, and the appearance is good.