Abstract: The rubber wood, Hevea brasiliensis (HBK) Muel is the most nondurable in Hainan Island. It is quickly damaged by decay fungi and termites as contacting with ground. The freshly felled wood which contains high moisture (60—80%) and some solventable sugars (around 5%) is subject to sapstain and damaged ambrosia beetles sometime. The dry wood is always damaged by many species of powder post beetles and dry wood termites. In warm moist atmosphere the mold is able to develop not only on surface of damp wood but also on dry wood. The results of the test indicate that: (1) The BBP Preservative (borax 35%, boric acid 30%, Na-PCP 35%) applied to build construction and furniture timber is the most effective in preventing decay fungi, mold, drywood termites and powder post beetles. The concertration of treating solution is more or less 55%. The preservative retention in treated wood should have 6—8kg/m^{3. (2) The BBP Preservative is safe to men, animale and environment but exist some irritation. (3) The hot-and-cold treatment which is being popularized at the state enterprises in Hainan Island is not only effective but also simple and easy to handle.}