Abstract: Aiming at the problems of unstable moisturizing precision of the post-expansion moisturizing machine for expanded cut tobacco and excessively high SD value of cut tobacco moisture after expansion, this paper analyzes and calculates the working principle of the moisturizing system of the post-expansion moisturizing machine, identifies the causes, and proposes an improvement scheme. By adding a water tank and replacing the water pipe diameter, the SD value of cut tobacco moisture after expansion can be effectively reduced, and the stability of moisturizing precision of the post-expansion moisturizing machine can be improved.