Block B of Wenchang 13-2 Oilfield is located in Pearl River Mouth Basin in the west of the South China Sea， and belongs to the offshore marginal small oil field. With the limitation of the number of slots and the rig capacity， and after comprehensive evaluation and in consideration of the actual development needs of Wenchang 13-2 Oilfield， three sections of ?339.7 mm flush joint casing were simultaneously run in ?914.4 mm conductor for the first time so as to realize the drilling and completion job of three wells independently from one slot. Taking the drilling of the B20， B22 and B23 wells from the slot as example， this paper systematically introduces the key triple hole splitter wellhead technology， including design principles， slot selection， directional well trajectory design， casing program design， surface casing running， surface casing cementing， etc. These key technologies have been successfully applied in Wenchang 13-2 Oilfield， providing reference and suggestions for improving the utilization rate of slots while effectively reducing the construction cost of offshore works in offshore oil and gas development.