According to the project requirements, wellhead water injection tests need to be conducted in the drilling process to detect its leakage and other failures based on the water absorption of boreholes and the pressure data. In the conventional way of wellhead water injection tests, drilling tools should be lifted out of the borehole, which severely affects the construction schedule. The development of the split type wellhead device allows the test to be done without lifting the drill string up, which is of great economic value and practical significance as it saves time, reduces labor intensity and safety accidents. This paper introduces the structure, working principle and application of the split type wellhead device developed for water injection tests without tripping the drilling string, and compares it with the conventional wellhead water injection devices through tests to verify its reliability and advantages.