Multi-layer alteration zones were encountered in the construction of ZK2-6 in Pobei mining area of Xinjiang, the longest continuous intense alteration zone was 30m. In the previous construction, the property of mud with brine was hard to be ensured, which was unfavorable to the wall stability and often caused hole wall spalling, diameter oversizing and drill pipe breaking, even borehole was abandoned. According to the drilling problems in alteration zone, the related research was carried out to put forward corresponding technical measures to complete ZK2-6 in Pobei mining area.