A series of finite element models were established and verified to study the compressive behavior of doubler or collar plate-reinforced square hollow section T-joints． The influence of the width of the brace and the thickness of the reinforcement plate was investigated． The control failure modes as well as the design formulas of the compressive capacity of reinforced T-joints were summarized． The parametric analysis indicates that the width of the brace and the thickness of the reinforcement plate are key parameters that influence the compressive behavior of doubler and collar plate，and they also determine the failure mode of the reinforced T-joints． When the width ratio of brace and chord exceeds 0． 8，or the thickness ratio of plate and chords more than 2． 2，the failure of the joint is dominated by the buckling of the chord side wall． Under this condition，it is unnecessary to further increase the thickness of the reinforcement plate． The proposed novel reinforcement method with collar plate is efficient to rein- force the flange and side wall of the chord，thus to prevent or delay the side wall buckling of the chord． The exist- ing design formulas from the literatures were finally introduced to calculate the compressive capacity of the plate re- inforced joints，and the applicability of each formula is checked and discussed