The visualization method of fruit tree branches that combines morphological information and parametric L-system is presented. Based on studying on the structures of pear tree, morphological characteristics, characteristics of ecological change and so on are extracted, then L-System model of pear tree including the thickness of the branches, bifurcation angle etc. are established, and geometric information of plant growth are transformed into intuitive graphical information and visual output through 3D modeling algorithm basing on OpenGL. Finally, we simulate basic forms of common pear tree (natural open center type, sparse layer of the main crown shape, small crown layer shape), which lays a foundation for developing the computer simulation system of pruning pear tree.