Soil total phosphorus (STP) plays a significant role in terrestrial ecosystem function. However, information about the distribution of STP and its driving factors in Acacia mangium Willd, plantation forests of the Southeastern region of Vietnam is still unknown. The study was performed to evaluate STP content and storage, and soil characteristics of three different-aged A, mangium stands (4, 7 and 11 years old). STP content was estimated in each stand at four depths (0-10, 10-20, 20-30 and 30-50 cm) according to the Vietnam National Standard method (TCVN 8940:2011). STP content increased significantly with forest age, from 2.38 g/kg in a 4-year-old stand to 3.57 g/kg in an 11-year- old stand. Furthermore, STP concentration principally occurred in the topsoil and declined significantly with depth. Phosphorus storage in the mineral soil layer (CP) increased significantly with stand age. Soil phosphorus storage revealed obvious surface aggregation, with more than 65% of CP being in 0 - 30 cm depth. Soil water content, soil bulk density and soil pH were the principal factors controlling the STP. The current study provides an overview of the distribution of STP as well as the effects of environmental parameters on STP.