Abstract: First-order branch characteristics,growth traits and stem form of populus hybrids(1-69*I-45)F1 clones were researched by divided the crown into three parts.Greater variation among clones for growth and branch traits are found. analysis on correlation and path shows that the ideal branch structure of I-69*I-45 F1 clones is:branch angle,branch lenth and branch number gradully increase from upper crown to down crown,less little branch in the upper and middle crown,more in the down crown. In the end of this poper,three types of branch structures ate classified.