Abstract: The reaming drill bit wrapped with mud in long-distance horizontal directional well will lead to drilling time delay and trajectory deviation from the original wellbore. And the effect of suction pressure on the wellbore wall during lifting drill bit can cause wall collapse, which affects the safety of downhole drilling tools and increases drilling time and cost finally. To solve this problem, this study summarized the construction experience, and combined numerical simulation theory experiments to improve the reaming drill bit. Industrial tests were carried out in drilling project of coal mine gas horizontal well in Shanxi province. Compared with the traditional reaming drill bit, the average drilling time was reduced by 38.9%, and the operation time and cost were also reduced.