The Greenspace of Udayana Mataram city is the smallest green area that should describe the endemicity of phytogeographic small Sundanese islands flora malesiana. The objectives of this research is to obtain basic data on the structure and composition of the Udayana green space and authenticity of the Malesiana flora in NTB province as a first step in determining the criteria and indicators of tree species suitability based on species autecological parameters. This research was conducted in January to Juli 2020 in the RTH Udayana. In this study, an overall stand inventory was carried out using the tree census method (100%). The sampling unit, trees with a diameter of ≥2 cm are identified and the diameter size (DBH) of trees height was recorded. The results showed that 64 species belong to 27 families, dominated by the Fabaceae family (27.39%). Besides, the results showed that 28.13% (18 species) of plants were invasive plants that had been recorded nationally and globally, namely tree habitus (P. longifolia, S. campanulata, T. mantaly, A. pavonina, B. purpurea, D. regia, E. crysta-galli, L. leucochepala, S. saman, T. indica, P. Americana, S. mahagoni, M. calabura, C. citrinus, F. decipiens, M. zapota), palm habitus (R. regia), dan woody bush (T. vulgaris). The type that dominates at the seedling and sapling level is T. mantaly with each IVI of (86.11% and 29.56%) with a highly dominance level. The highest IVI value at the pole level is (29.54%) with moderate species dominance level and tree-level was dominated by Samanea saman with IVI value (59.33%) with high species dominance level. The species dominance index (C) is in the range (0.00012-0.24) indicated there is no concentration of the species in the plant community in RTH Udayana. Ecology index showed at seedling level H’=1.29 (low), E’=0.21 (low) dan R’=1.04 (low); Sapling level showed H’=3.21 (moderate), E’=0.93 (high) dan R’=5.23 (high); Pole level showed H’=3.61(high), E’=0.58 (moderate), R’=7.76 (high); and Tree level showed H’=3.52 (high), E’=0.90 (high), R’=7.33 (high). The horizontal structure of the stand shows the tree density decreasing exponentially as the diameter of the trunk increases. Vertical stand structure shows that canopy stratification in RTH Udayana is found mostly in stratum C (121.31 ind/ha), followed by stratum D (5.80 ind/ha) and stratum B (3.43 ind/ha).