By taste analyzer, the physical and chemical data of brown rice was obtained. And then, employing the model of white rice, the correlation between the main compositions and taste value was gained by parameter estimation. Base on the paddy moisture falling to 15%, a mathematical model for taste value of the brown rice was built by using quadratic orthogonal rotation combination design to evaluate the rice taste quality and develop the vacuum drier. The research results showed that drying temperature, original moisture, and vacuum degree are the key factors affecting the taste value during paddy vacuum drying, according to priority. The taste value is negatively related to the two former and is positively related to the latter.