The utility model provides a post -cast strip structure of overlength super large area bottom plate. The post -cast strip structure is including setting up in two I -steel of post -cast strip both sides, sets up between two I -steel web inboards the tortuous steel sheet as absorbing the carrier that warp to and attach the stirrup in the web outside of two I -steel every 15cm~25cm's interval welding, be the post -cast strip scope between the two I -steel webs promptly. The utility model discloses an interval sets up tortuous steel sheet in the overlength post -cast strip, can be out of shape the shrinkage strains that buffer absorbs to come from the post -cast strip both sides and water earlier the concrete as one kind on the one hand, and on the other hand had both realized the disposable concreting construction in succession of overlength post -cast strip as being out of shape isolating device overlength post -cast strip along the great shrinkage strains of its length direction accumulation that can effectively weaken, had avoided the disposable overlength in post -cast strip to build the fracture risk that probably produces again.