Abstract: The large size double-web box beam with various holes at bottom flange is analyzed by using finite element method. The law of stress-strain and mid-span deflection is investigated regarding the width and position of holes as variables. Results show that the mid-span deflection is intensive along with the holes moving toward mid- span and the width increment of holes. When the distance from hole to steadier exceeds 30% of the beam length, the normal stress of the mid-span will greatly weaken. But if the distance is less than 30% of the beam length,the influence of holes on normal stress of mid-span wont make much difference. The normal stress of profile in bottom flange and the difference between mechanics of materials and finite element analysis results increase as the width of holes increases,but the difference in the shear strength of this profile is approximate. At last,a simple comparison is made between FEA results and materials mechanics results, and the correction coefficient is thus obtained for design.