A　longan　(Dimocarpus　longan　Lour.)　growth　and　development　simulation　model　was　created　by　integrating　existing　knowledge　of　different　aspect　of　the　Longan　architecture　and　physiology.　Field　investigation　and　measurements　were　conducted　in　longan　orchard　in　order　to　acquire　architectural　characteristics　of　longan　tree.　The　three-dimensional　canopy　model　of　longan　is　consisted　of　trunk,　branches　and　leaves.　The　basic　unit　of　stem　is　a　parameterized　segment.　The　3D　segment　was　described　with　cone.　The　leaves　were　depicted　using　parametric　NURBS　surface.　The　3D　canopy　was　presented　by　connecting　the　elements　according　to　the　tree　architecture　and　topology.　Hourly　photosynthesis　per　leaf　under　various　environmental　conditions　was　calculated,　and　the　total　photosynthesis　assimilation　of　the　young　longan　in　growing　season　was　estimated.　Based　on　source-sink　partitioning　theory,　the　biomass　was　allocated　among　organs　according　to　the　organ　expansion　rate　and　age.　Tree　growth　is　driven　by　the　available　photosynthetic　products　after　respiration　losses.　The　development　of　longan　was　reshaped　by　expanding　of　existing　organs　or　generating　new　organs　corresponding　to　the　increments　of　assimilation.　Thus,　the　simulation　of　the　dynamic　growth　processes　of　young　longan　under　certain　environmental　factors　was　realized.　A　Tree　growth　simulation　prototype　system　was　implemented.　It　includes　modeling　of　tree　morphological　structure,　accumulating　and　partitioning　assimilation　products　among　different　organs,　and　visualizing　the　partitioning　outcome.　The　simulation　of　fruit　tree　growth　in　virtual　plant　environment　will　be　useful　to　understand　the　longan　growth　and　to　develop　strategies　to　improve　fruits　production.