Abstract: Mixed metal hydroxide(MMH) could be used to inhibit the hydration of clay mineral and coal rock,mean- while,surfactants can be used to enhance the hydrophobicity of reservoir rocks. Comprehensive evaluation on the prop- erties of water-based drilling fluid which could enhance the wellbore stability of coal measure strata in the co-exploita- tion of “three gases” was conducted. Results show that inorganic MMH-1 had a good electrical inhibitive performance. The contact angle of composite surfactants solution with coal sample is 102°,and the contact angle with shale is 91°, which shows that the composite surfactants solution could obviously enhance the hydrophobicity of coal rocks in coal measure strata. Compared with fresh water,the composite surfactants and inorganic MMH-1 can significantly retard the pore pressure transmission speed in coal rocks and shale,and decrease the permeability of rock samples up to 99% . Inorganic MMH-1 and composite surfactants have a good compatibility with water-based drilling fluid. The contact an- gles of the optimized drilling fluid with coal and shale are 77． 5° and 66. 5°,respectively. It has excellent hydration inhibition and salt resistance,good tolerance to temperature and pollutants( inorganic salts,drilling cuttings),and very low reservoir damage rate(3. 8% ) to the original coal. The achievements of this paper can provide a guideline for the design of water-based drilling fluid in the co-exploitation of “three gases” in coal measure strata.