Abstract: By Research of ‘Xinwen185’ Evacuation layered shape Trees Crown inner layer Light distribution, Aimed at depth and comprehensive understanding of the relationship between leaf area index and light transmittance within walnut Crown inner layer. Using the US LI-COR company"s LAI-2000 canopy analyzer before sunrise and after sunset, determination leaf area index (LAI) and light transmittance (Tr) in the divided small cubes at the tree crown. Experiments Sample tree Crown layer inner light transmittance follow Seasonal changes in vertical distribution of is Middle> upper> lower, And between Layer Change range also relatively close; horizontal distribution is external> central> bore, further is bore and middle difference is small. The extinction coefficient of Crown layer inner follow Seasonal changes showing it has maintained an increasing trend from no leaf stage to the lipidated stage. From Leaf expansion period to Rapidly growth period and from Rapidly growth stage to the lipidated stage,Them extinction coefficient appeared the growth rate a great changes. By determine the leaf area index can be drawn about the crown inner layer walnut light transmittance, and thus obtain the extinction coefficient, in addition extinction coefficient the largest stages is in the from leaf expansion period to the lipidated stage.