This paper describes a fast and efficient 3D method to emulate trees with parametric Lsystem.The emulation was performed in three stages.First,parametric Lsystem was employed to construct the initial skeleton of tree by analyzing the tree abstract model,and the tree skeleton was optimized by Hermite curve fitting.The second stage was 3D emulation of the tree.A 3D mesh model of the tree was reconstructed with the help of Frenet frame and the associated 3D geometric theory under the constraints of the optimized skeleton and branch radii generated by Parametric Lsystem.Finally the 3D model was completed in combination with the simplified model of leaves.Experimental results show that the proposed emulation method for 3D trees not only reduce the amount of tree model data effectively,but also can limberly emulate many kinds of trees models.