Because of the complex formation structure in oil shale mine, collapsing, block falling, diameter shrinkage and loss of drilling fluid often occur in the drilling operation, which make difficulties in core sampling with bit burying, sticking and burning. By the comprehensive analysis and experiments, the drilling fluid compound method with good inhabitation is selected for Yudaokou oil shale formation, the satisfied effects and ideal economic benefit are obtained, and a large amount of experimental data are collected to be technical reference for the drilling operation in similar mines.