Abstract: Initial deflection of the floor beam of a project by lateral loads and co-axial role occurs because of the construction defects.Based on the analysis of the initial defect of the beam,it is derived a formula for stability bearing capacity of the bending members under lateral loads,and makes a conclusion of the bearing capacity and normal performance of defective beams that the defective beams with no special treatment are still safe.The analysis process of the defective beams can be a reference for similar projects.