Abstract: Due to the constraints of platform conditions, water treatment capacity and reserves scale, the secondary development of BJT oilfield in East-China sea can not be achieved by water injection as onshore oil fields. In order to improve the oil recovery of the H4B thin oil layer which is only driven by the elastic drive, the upper aquifer is connected to the oil layer through side-drilling in the adjacent well, and the upper water with sufficient energy is used to replenish the reservoir energy and realize drainage between layers. Due to the water dumping, the reservoir pressure and oil production have been vigorously maintained by production observation. Through the low developing speed and periodic production system, the pressure between the reservoir and the aquifer has been balanced, and the oil recovery of the thin oil layers has been enhanced. It provides an important reference for the development of similar reservoirs.