Abstract : Research purposes ： Because of different rigidity distribution，shear - lag effects in PC box - girder with corrugated steel web are different from that in PC box - girder. In order to investigate the shear - lag effects in twin - cell PC box girder With corrugated steel web，3 D finite element model of twin - cell PC box - girder With corrugated steel web was founded by means of ANSYS，and stress distributions on typical sections were obtained. Shear - lag effects of twin - cell PC box - girder with corrugated steel web were investigated，which is compared with the ordinary PC box girder. Seven geometric parameters affecting the shear - lag effect of box girder were analyzed. Research conclusions： (1 ) Using corrugated steel web can enlarge the maximum shear lag coefficient of each section slightly. (2) In term of the top flange，the shear - lag coefficient of the medium web is larger than that of both sides， contrary to the bottom plate. (3 )The width length ratio，the support length of the box - girder，and the thickness of the roof were confirmed as the main factor working on the shear - lag effect，and the shear lag was not influenced by the number of the diaphragms. (4)The research result are worthy of use for reference for design and analysis of PC box - girder with corrugated steel web.