Abstract: In order to grasp the construction error laws of bedding gas drainage boreholes, the deviation between drilling trajectory and design trajectory was theoretically analyzed. The “opening deviation” and the “shape deviation” form the borehole “construction error”. Based on YCSZ（A）rotary drilling trajectory measurement system, the bedding gas drainage borehole trajectory is measured and analyzed. The research results show that the “opening deviation” and “shape deviation” increase with the increasing of drill hole depth in both horizontal and vertical directions, and the deviation direction takes on randomness; “opening deviation”, “shape deviation” and “construction error” of borehole in horizontal are greater than that in vertical; the borehole construction error in horizontal is closely associated with “opening deviation”, but the difference between “opening deviation” and “shape deviation” in vertical is not obvious. On the basis of testing results, the precaution measures are provided.