自从在测树工作中使用直径围尺以来,围尺测树和轮尺测树的关系引起了人们的重视。从发表的材料来看,一般围尺测径值总是大于轮尺测径值。但是,这个差值的大小和产生差值的原因众说不一。本文试图从理论上对这个问题做一探讨。主要证明不管树干形状如何, Since the use of diameter ruler in measuring trees, the relationship between ruler and caliper tree has aroused people’s attention. From the published material point of view, the general circumference caliper value is always greater than the caliper diameter value. However, the difference between the size and the reasons for the difference between different. This article attempts to make a theoretical study of this issue. The main proof no matter how the trunk shape,