There are some sho rtcoming s in t radi tio nal methods of structural analy sis based o n pin-jointed truss members and beam elements, such as inaccurate descriptio n o f co nnection among the members of t russ and betw een the members and deck system, a nd ov erloo king effect s on cross width of members of truss. Suitability of all shell elements mo del in steel bridg es i s a naly zed in this article. The method o f establishment a nd implementatio n o n this computing model of 3-D st ructural analy sis in long spa n steel bridg es is presented. The new model i s univ ersal in the computatio n of steel bridg es.