Prestressed concrete double Tee floor slabs are widely used for the roof of building construction. Some problems are met during the development practice of this type of precast structures. Firstly, the overhang flange of the traditional double Tee floor slab is not enough large in the view of economic and utilization. Secondly, it is not easy to dispose the skylights on the roof used double Tee floor slabs in the workshops or the gymnasiums. Thirdly, most of the beams are produced in prestressing plants, but very few productions are made in site. Therefore, a new type of prestressed concrete double Tee floor slabs have been designed with some characters such as 3.0-m outside flange, flange slabs with rectangular opening holes for the skylights or not, and the beams produced in the prestressing plants with pre-tensioning prestressing tendons or post-tensioning with the strands in site.