In order to meet the necessity of the code for seismic design of buildings: Principle for strong connections and feebleness member. The exernal steel tube of column and steel beam are joining with three kinds of style. Containing two strengthen styles T-style stiffening plate and appending haunch. The result reveals that the two strengthen connections ultimate load are much bigger, good ductility, better seismic behavior. The deformation of the column and the region of the connection is smaller when it was broken, Indicating the connections’s globality is better and the stiffness is bigger. It avoids brittleness for breaking styles when they are given more load.