Abstract: Proposed a trees simulation method with diameter variety rate. Based on L system, incorporated diameter variety rate of tree's branches and trunks into the tropism mechanics model,applied parameters to control branch's part shape and space location. The different species depent on the relation between the parameter and diameter variety rate.The method can control the tree's final shape conveniently, and generate the graphs which are more idyllic.

Key words: Tree simulation,L system,Diameter variety rate,Tropism