相对干率是一种新的干形表示方法，用此方法表示泡桐的干形，可使真实的树干转化为统一标准的圆柱体，并能够排列在一张图上实现直观图示。本文着重分析研究了７个泡桐种、无性系及其以桐杂一号为代表分别在不同生长阶段的干形差异，并且找出了材积结构的动态变化规律．首次提出用Ｘ０．９值简捷有效地分析评价泡桐干形优劣的方法。 Relative dryness is a new dry form of representation, using this method to indicate the dry form of Paulownia, which allows the true trunk to be converted into a uniform standard cylinder and arranged in a diagram for visualization. This paper focuses on the analysis of seven Paulownia species, clones and the Tongsheng one at different growth stages were dry-shaped differences, and found the volume structure of the dynamic changes. It is the first time to propose a simple and effective method to analyze and evaluate the advantages and disadvantages of dryness of paulownia with X0.9 value.