Design and development of Penglai oilfield two period 40 slots (16 dual bore slots) wellhead platform can drill 56 wells. By far, it is the most number of Bohai offshore drilling platform. On the basis of slots and Christmas tree surface layout, considering the design of directional well and the anti-collision problem, this paper describes the installation of the surface casing and cementing procedure. The 56 wells slots drilled from a 40 slot WHP reduces the number and cost of the platform while providing additional wells to meet the reservoir development plan. Thus it plays a guiding role of the development of subsequent oilfield.