The shale hydration and dispersion are the major factor which reasonable for the wellbore instability and the accidents such as tight hole, stuck pipes and borehole collapse. Compare to sodium methylsiliconate, potassium chloride, sodium silicate and potassium silicate, potassium methylsiliconate exhibit better shale inhibition, through clay settlement test, bentonite inhibition tests and linear swelling tests. The shale inhibition mechanism of potassium methyl-silicate was investigated by infrared spectroscopy, X-ray diffraction, water-contact angle and optical microscope. The excellent inhibition effect and collapse preventing of potassium methylsiliconate is attributable to the synergistic effect of potassium cation and hydrophobic membrane structure formed on the surface by methylsiliconate anions.