Abstract: Ying-hua Palace in the Forbidden City is taken as an example.FEM of Chinese ancient wood structure is built on the basement of hypothesizes that tenon-mortise joints are considered as semi-rigid elements and tou-kungs are considered as 3-dimensional springs.By modal analysis the first 10 periods as well as vibration modes are obtained.Then Tianjin seismic waves in 3 dimensions are input and response curves of typical nodes as well as elements are studied.Aseismic characters of constitutions such as tenon-mortise joints,tou-kung and ce-jiao are discussed.Results indicate that base frequency of Ying-hua Palace is low,whose main mode in x direction forcuses on No 1 and No 2 on y direction;Under seismic forces responses of roof are weaker that those of top of columns;Constitutions of tenon-mortise joints,tou-kung and ce-jiao are helpful for seismic resistance of ancient structure.