A novel Gemini-surfactant type small cationic shale inhibitor: N1, N2-didodecyl-N1, N1, N2, N2-tetra (2-hydroxyethyl)-dibromoethane diammonium (Gemini-DHEDB), was prepared with diethanolamine, bromododecane and dibromoethane by Two–Step Method. Linear expansion tests, rolling recycling tests and sedimentation stability analysis tests were utilized to study its inhibition property, respectively. Results showed that the linear expansion height of sodium montmorillonite (Na-MMT) and the shale rolling recovery rate of shale was were just 4.27 mm and 52% in Gemini-DHEDB solution (mass concentration of, 2g/L) after 16h. , which were superior to the results in 2g/L dimethyl diallyl ammonium chloride (10.62mm, 31%), 2g/L tetrabutyl ammonium bromide (9.41mm, 36%) and 2g/L 3-methyl-2-hydroxyethyl ammonium bromide solution (7.74mm, 41%).Meanwhile, the linear expansion height and shale rolling recovery of dimethyl diallyl ammonium chloride, tetrabutyl ammonium bromide and 3-methyl-2-hydroxyethyl ammonium bromide solution was 10.62mm (31%), 9.41mm (36%) and 7.74mm (41%), respectively. , In sedimentation stability analysis tests, the Completion sedimentation completion sedimentation time of fresh water based fluid was about 14 h and the final thickness of sedimentation is was 38mm, while upon the addition of Gemini-DHEDB, the sedimentation time was obviously reduced to 1.2 hours and final thickness was 1.2 h and 45 mm. The micro structures of sodium montmorillonite (Na-MMT) composites were characterized via FT-IR analysis, X-ray diffraction (XRD) and scanning Scanning Electron Microscopy (SEM). Characterizations demonstrated that the successful intercalation and adsorption of Gemini-DHEDB into the Na-MMT interlayer, and had changed the micro structures of Na-MMT and the successful incorporation of Gemini-DHEDB with Na-MMT.