The geological conditions of Hole 23-2， detailed investigation of coal resources in Tuhongwan-Lijiagou， Baiyin City， Gansu Province are extremely complex， including mudstone with strong water sensitivity， loose and broken coal seam， etc.， and salt paste in between， the hole is prone to collapse， clumping and other problems， and the drilling fluid is easy to be polluted， which puts forward higher requirements for drilling fluid properties. In the past drilling construction of this mining area， problems such as hole wall collapse and significant reduction of drilling fluids viscosity often occurred， which in serious case led to buried drill， solids setting stuck and other drilling accidents， and thereby affecting the efficiency of hole-forming and construction efficiency. In view of the above problems， the causes of borehole wall instability when drilling are analyzed， the effects of salt-paste penetration on the properties of the drilling fluids are evaluated， the adaptability of the system is studied in a targeted way and the film-forming anti-collapse drilling fluids and salt-paste encroachment film-forming environment friendly drilling fluids are selected. During the driiling process， aiming at the water sensitive and spalling and loose strata， the film-forming anti-collapse solid free dilling fluid was selected， and transferred to salt-paste encroachment film-forming environment friendly drilling fluid when encountered salt encroachment. Moreover， technology such as reasonable adjustment and maintenance of drilling fluid formula and performance parameters， wire-line core drilling are adopted to solve the above problem.