Abstract: A driving unit for a caulking gun includes at least two push portions respectively located on two respective rear ends of at least two tubes of a dual-tube unit so as to push material in the at least two tubes toward an outlet on a front end of the dual-tube unit. At least one connection portion is connected between the at least two push portions and a blade is formed on the front end of the at least one connection portion. The blade cuts two adjacent walls of the dual-tube unit so that the at least two push portions are moved forward when the driving unit is pushed forward. The materials in the at least two tubes are mixed and quickly solidified.