Abstract: This paper deals with light interception character in Populus deltoides instraspecific hybrid F: clones. The results are as follows: the main factors that influence light energy utilization of population and individual are leaf area index, light extinction coefficient, the capacity of light interception and lamina angle. Analysing on heritability and genetic correlation shows that all above tratis are of great value to growth and genetic improvement. In this population, the middle crown plays the most important part in tree growth, the ideal crown structure of Populus deltoides is more leaf area index of upper crown, less leaf area index of middle and lower crown and more horizontal lamina angles.