Abstract: In view of the complex problems of hole wall collapse, diameter shrinkage, stuck drilling and buried drilling caused by loose and broken rock strata and hole wall instability, during drilling in coal measure mud shale complex strata, the flushing fluid treatment agent is analyzed by single factor test Cellulose (CMC), polyacrylamide (PAM), sulfonated asphalt (SAS) offset the effects of rheological properties (funnel viscosity, plastic viscosity, dynamic shear force, apparent viscosity, fluidity index, consistency coefficient) and water loss properties of the lotion, and obtained the final optimal formula of the lotion by orthogonal test.The final optimized formula is 5% clay+0.3% sodium carbonate+0.5%CMC+0.04%PAM+2%SAS, has been applied to the drilling of coal measure mud shale complex strata in Huize lead-zinc mining area in Yunnan Province, and achieved good production results.