Abstract: In Sichuan Basin and Tarim Basin, the designed drilling flow rate of deep well and ultra-deep well upper large hole vertical well section reaches 55～150 L/s, which greatly exceeds the adaptable range of existing MWD tools in the industry, and the problems of serious tool erosion, failure rate and high cost are prominent. In order to solve the problem of high efficiency and low cost monitoring while drilling in the vertical section under harsh working conditions such as large displacement and strong down hole vibration, a new type of rotary valve with large channel erosion resistance was designed and developed by means of expanding the flow area, simulation optimization of flow field distribution and local carbide protection in the area of intense erosion. Multistage composite vibration reduction methods such as flexible suspension fixing of accelerometer and silicone potting adhesive of circuit board are adopted to improve the vibration resistance of tool electronic circuit. By designing fast transmission code, low power electronic circuit and energy-saving operation mode, the Inclination monitor efficiency and tool endurance are improved. On the basis of the above key technological breakthroughs, a series of high displacement vertical well inclination measurement tool is developed. The research and application results show that: the tool has strong resistance to large displacement erosion, and the maximum applied displacement has reached 120 L/s; Stable and reliable operation, field application failure rate is less than 0.5 times/month; Long life, up to 30 days or more. The field application of the tool provides strong data support for the successful drilling of high-quality vertical well sections with a inclination of less than 1° in the ShenDi XX well of the 10,000 meters deep geological exploration project of the CNPC under the conditions of 110～120 L/s large displacement radical drilling parameters.