The invention discloses a precise characterization method for water at an outlet of baked cut tobacco. The precise characterization method comprises the following steps: setting response time of an in-line infrared water-measuring meter to be 1-30 s; respectively collecting unprocessed original data and processed output data of the in-line infrared water-measuring meter, controlling data for PLC filtering processing and data of an upper computer; analyzing the collected data by adopting different data smoothing rules, and determining a data processing rule of the water-measuring meter preliminarily; and verifying by comparing through a baking box method and a water-measuring meter measurement method, and finally determining the data processing rules of the water-measuring meter. With the adoption of the precise characterization method provided by the invention, the true value of the water at the outlet of the baked cut tobacco can be accurately reflected, and thus the cut tobacco baking process is well controlled.