The invention relates to an assistant device, in particular to an assistant device for opening an ampoule bottle. In order to achieve the technical purposes that the operation is simple, and the handscan be prevented from being injured, the assistant device for opening the ampoule bottle comprises a base, an inverted L-shaped plate, an installation block, an arc-shaped support, an annular slidingrail, a rotary slider, a motor, a rotary shaft, an installation rod, an installation base, a knife blade, a vertical sliding rail and the like. The right side on the top of the base is connected withthe inverted L-shaped plate and the installation block, the inverted L-shaped plate is located on the right side of the installation block, the left end of the inverted L-shaped plate is connected with the arc-shaped support, the lower portion on the right side of the arc-shaped support is provided with the annular sliding rail, and the annular sliding rail is slidably provided with the rotary slider. Through rotation of the knife blade, the ampoule bottle can be carved, so that the operation is simple; it is not required that a medical worker carves the ampoule bottle with a grinding wheel so that the hands can be prevented from being injured; the knife blades with different lengths can be replaced, and accordingly, the ampoule bottles with different sizes can be carved.