The invention discloses a moisture regain method of tobacco stem particles, comprising the sequential steps of charging, evacuating, introducing saturated steam, moisturizing to regain moisture, and discharging. According to the moisture regain method of tobacco stem particles, a moisture regain room that is charged with material is evacuated to a set value, saturated steam is then introduced into the moisture regain room, tobacco stem particles regain moisture fully and evenly in vacuum state, the tobacco stem particles regained moisture have uniform moisture, and the moisture regain efficiency is high; cellular cavities in the tobacco stem particles are enlarged, the features of the particles as a macroporous adsorbing material are enhanced, good adsorbing capacity is provided, scorch smell of the tobacco stems can be removed effectively, smoke is elegant and fine, the tar and CO discharges are decreased effectively, and internal quality of the tobacco stem particles is improved.