In the coal bed was mad in the vertical shaft well drilling, has the well slanting exceeding the allowed figure phenomenon frequently,Pulls out the platoon for the later period well drilling construction and the coal bed gas to pick brings many adverse effects, serious also possibly causes the bore hole abandonment. Therefore, the analysis creates the well slanting primary causAbstract: In the coal bed gas exploration well drilling, the well slanting exceeding occurs frequently, which has adverse effects for the coal bed gas extraction, drainage and collection in later period, even can lead the bore hole abandonment. Therefore, the analysis on the primary causes of well slanting and taking the practical technical measures to prevent well slanting are important to improve drilling efficiency and engineering quality, reduce drilling cost and speed up coal bed gas exploration development. Combined with the coal bed gas drilling practice, the primary causes of well slanting are briefly analyzed and the concrete preventive measures are put forward.