Due to the need of the function as a construction, container houses are usually required opening treatments in practical engineering, which will influence the whole lateral stiffness significantly. To get the lateral stiffness theoretical calculation formula of container house with openings, this paper studied the reduction factor from the influence of openings on the corrugated skin structure welded on four sides. Based on the diaphragm theory of Europe, the forms of openings were limited and the corresponding calculation formula of the reduction factor was deduced. Then the finite element model built with ABAQUS was adopted to verify the theory, and for the three limitations which were most easily to be exceeded (the height\\shape of window and the position of door) were analyzed. Through the existing experimental data, the proposed finite element model was verified. The results indicate that the window type openings cause the obvious stress concentration at the place close to openings, so corresponding deformation increases and overall lateral stiffness is reduced, while the reinforcement of openings can effectively reduce this tendency. In practical engineering, a circular window should be considered firstly instead of rectangle one, the smooth and symmetrical shape of which can weaken the stress concentration compared with the rectangle shape under the premise of the same area. Door shaped opening is sensitive to the position, and it should be center layout to reduce obvious local effect.