After a period of use, vertical deflection and transverse tilt happened to the alcohol tanks due to some reasons such as the deformation of foundation, and the deflection or tilt would result in the change of its capacity chart. In order to measure the capacity of the alcohol in the tanks accurately, we need to recalibrate the capacity chart of the alcohol tanks periodically. First, we abstract the actual alcohol tank into a small elliptical mathematical model with a vertical tilt angle α and use it to research the relationship between α and the capacity of the alcohol tank. Then, we extend the mathematical model to reality, and give a large number of actual data. According to these characteristics and reasonable assumption, we achieve to the identification of position and re-calibration of capacity charts by using the Matlab software to analyze and fit the large amounts of data.