The utility model belongs to the field of medical instruments, and particularly relates to a precise adjusting device which is mainly used for the precise adjustment of infusion speed in an infusion apparatus. The precise adjusting device is characterized in that an adjusting sliding block and an outer shell formed by connecting an upper cover and a lower cover are included, the upper cover is provided with a strip-shaped groove, scales are arranged on one side of the strip-shaped groove, a liquid inlet channel, a liquid outlet channel and a sliding block groove are arranged on the lower cover, the liquid inlet channel and the liquid outlet channel are respectively communicated with the sliding block groove through a liquid inlet and a liquid outlet, the adjusting sliding block is composed of a sliding block body and an adjusting button fixedly arranged on the sliding block body, the sliding block body and the adjusting button are arranged in the sliding block groove and the strip-shaped groove respectively, an infusion channel is arranged in the sliding block body, and the inner wall of the infusion channel is an inclined face. The precise adjusting device is simple and reasonable in structure and easy and convenient to operate, in the infusion process, proper infusion speed is determined according to liquid medicine varieties and the condition of patients, the adjusting button is slide to the corresponding scales, the precision control over the flow speed of liquid medicine can be achieved, and the precise adjusting device is suitable for large-scale popularization and application.