The geological conditions were extremely complicated with poor wall stability in WFSD-2 hole drilling construction of Wenchuan earthquake fault scientific drilling project. Due to the water-sensitive formation of mineral water swelling, broken strata and stress release, the hole wall necking, collapsing and leakage happened many times. Through the adjustment and maintenance of the formulation, parameters, and solid control, LBM-GLA drilling fluid system with a low viscosity synergy powder and modified asphalt as the main raw materials was adopted in the construction; the above problems were successfully solved. This article mainly describes the use and maintenance of drilling fluid in each section of WFSD-2 hole.