Abstract: Sidetracking of low-efficiency wells is one of the main methods for stabilizing and increasing production in Bohai Oilfield. Reasonable matching of inefficient well slots and sidetracking positions is the first measure to reduce costs and increase efficiency. This article takes three low-efficiency wells in an oilfield in Bohai as an example. We match the slot of the inefficient wells and the sidetracking wells by analyzing their positional relationship. And a slot optimization design method is formed according to the changes of the full-angle change rate, inclination angle, azimuth, the inclined section length, the depth of the well, the footage, and etc. The on-site implementation results show that the application of this method can choose a less difficult plan, saves more than two million yuan in cost. The three inefficient wells slot optimization plans in this oilfield are reasonable, and the difficulty and costs of operation are reduced. Finally, a set of optimization design methods for sidetracking notches in Bohai Oilfield have been formed, which can effectively reduce the difficulty and costs of operations and provide a reference for the optimization of sidetracking notches in Bohai Oilfield.