Abstract: Hole slanting control has been one of the most remarkable difficulties. Through many years of research, the vertical drill-ing system, BH-VDT 5000, was developed. The structure, operational principle were introduced, and its application process and effect in Well Keshen 203 in Tarim oilfield were analyzed. The second section of Well Keshen 203 was finished in two runs using BH-VDT5000 system and the total footage was 1 558 m, and the inclination is controlled within 0.5 degree. Compared with the adjacent wells drilled by the Power-V vertical drilling system, the average rate of penetration was 23% higher. So the conclusion was that BH-VDT5000 sys-tem can promote the rate of penetration, shorten the drilling time and satisfy the requirement of slant prevention and fast drilling in high dip angle and thrust over nappe formation, therefore, it can be used further.