Abstract: The hybrid steel girder,which is very economic,has good prospects in the field of bridge engineering.To fully understand the mechanical properties of hybrid steel girder,this paper conducts an intensive study of response process,bending and shear bearing capacity based on numerical analysis.A rational ratio of web-flange yield strength considering the effect of web yield strength is proposed.Formulae for calculating the elastic-plastic deformation of hybrid girders are constructed.The critical flexural-torsional buckling moment is studied by means of non-dimensional coordinate system.And the solution to flexural-torsional buckling analysis of hybrid girder is given by proposing the regression equation of elastic-plastic section and two limiting relative slenderness ratios.After comparing different formulae of previous researches,the AASHTO 2004 method is recommended for calculating the shear bearing capacity of hybrid beam.Considering the conservative of shear calculation result of end panel by the AASHTO 2004 method,the revised formula considering the effect of aspect ratio is developed.And a new formula for calculating shear strength considering the effect of bending is proposed as well.The calculations involved in design of hybrid steel girder are basically made.