Abstract: The influence of the volume change of vertical tank on liquid block measurement precision has not be conquered ever since. This paper, through analysis on the three basic states and increment of bottom volume, introduces the concept of bottom deformation pattern, and presents the curve of deformation pattern. The curve consists of the following three zones: ①The bottom plates in Zone Ⅰ will experience no detormation when the tank is filled, therefore, no volume increment will occure and the strapping table for the empty tank will keep valid; ②Zone Ⅱ is a zone of elastic deformation, where the bottom volume will increase and change constantly, resulting in variable level-volume relation and the invalidation of strapping table; ③Zone Ⅲ, being a stable zone, will have a stable state of bottom plates and a constant volume increment, and it is required to carry out a strapping table correction for real tank volume to replace the invalidated strapping table for empty tank. Once the critical points for the three zones and the increments for Zone Ⅱ and Ⅲ are available, the corresponding change pattern of bottom volumetric increment can be determined. The measuring method and strapping table obtained on the basis of this pattern can achieve a measurement precision of 0.1%.