Abstract: With the application and promotion of drill pipe screen insertion technology, the normal four-winged on-off PDC drill bit has the disadvantages of low drilling efficiency in through beds hole section, and the center blade can't open properly because of its distortion. In order to solve this problem, a new three-winged on-off PDC bit was designed, and the field test was carried out in Zhu ji dong coal mine of Huainan Ming Group, the average drilling footage was 590.7m, the average life expectancy increased by 68.8%; the average drilling efficiency in through beds hole sandstone section increased by 33%, and the success rate of casing job reached up to 100%.