Abstract: In this paper,numerical simulation was used to study the relationship between the advanced drill hole's diameter at coal roadway heading face and the front coal destressing effect.It indicated that with the increasing of the advanced drill hole's diameter,the geostress of coal in front of heading face decreased,plastic zone was decrescence and the destressing effect was more outstanding.The test,about construction of large-diameter hole in tunneling process of Wulan coal mine 5867 machinery tunnel,showed that using large-diameter hole can decrease the number of holes by 2/3,shorten the construction period about 7 days and increased coal roadway tunneling speed four times above.