Abstract: At present, the secondary distribution in tankfarm is mainly conducted by way of unreasonable administrative regions. The distribution scopes from tankfarm to gasoline stations and users (namely tankfarm distribution region), should be optimized. Therefore, based on the theory of Thiessen-Polygon, the distribution region of in-service tankfarms in an area is re-classified, considering the characteristics of Thiessen-Polygon and according to the construction step of Thiessen-Polygon. Specifically, 15 in-service tankfarms in that area are defined as reasonable distribution region. Distribution region result of each tankfarm is limited by the area boundary constraints. Taking the boundary factors into consideration, several virtual regions are divided according to geographical position, which is convenient for management and oil distribution. It shows that, given the unchanged tankfarm configuration and distribution mode, the total average distribution distance of entire tankfarms decreases by 10.54% after distribution region optimization.