Abstract: The new kinds of environmental drilling fluids were introduced at the first. Then the author detailed a new kind of environmental drilling fluid which was called auto-degradated drilling fluid. It has excellent holding and blocking performances in drilling process, while can be auto-degradated at the end of drilling work. Finally, the several applications of auto-degradated drilling fluid in Gansu province Zhangye city and Guangxi province LiuZhou city was introduced in detail. The practice made sure that it can solve the contradiction of protecting the hole and recovering the filtration of the formation in water well works.