The descriptions of this paper was included the following contents, (1) The wood species were used in the traditional ancient wooden construction building in Taiwan, (2) White-rot and brown-rot fungi were used in the accelerted decay resistance tests, and the natural decay resistance of wood species were classified according to their weight loss percentages, (3) The wood preservatives for decay resistance and their testing methods, (4) The effect of wood preservative treatment on the improvement of decay resistance, (5)The effects of wood preservative treatment on environments and biological bodies, (6) In the future, a system must be established in order to maintain the ancient wooden construction buildings.