The invention aims at providing a three-color-liquid-silica-gel injection molding device. According to the three-color-liquid-silica-gel injection molding device, the multi-cavity individually driving method is adopted, and according to a gear changing box, single driving or two-shaft driving or three-shaft simultaneous driving of screws in three injection molding cavities is achieved, and three-cavity simultaneous injection molding or single-cavity injection molding or double-cavity injection molding is achieved. According to the three-color-liquid-silica-gel injection molding device, transmission gears of three screw pump screws are driven by a middle sliding gear, three pump shafts are independent, and each pump shaft is transmitted by a transmission shaft and a transmission gear. The three-color-liquid-silica-gel injection molding device is composed of a middle transmission spline shaft, a first-cavity transmission shaft, a first-cavity transmission gear limiting sleeve, a first-cavity transmission gear, a sliding gear shifting fork, a middle sliding gear, a second-cavity transmission gear, a third-cavity transmission gear, a middle sliding gear limiting sleeve, a first-cavity screw shaft, a connecting transition disc, a screw front-end bearing, a pump, a first-cavity screw, a control rod and the like. By means of the three-color-liquid-silica-gel injection molding device, the simultaneous injection molding problem of multi-color liquid gel can be solved, the structure is reliable, and using is convenient.