Abstract: Ground calcium carbonate powder（GCC）was modified with poly（maleic anhydride-acrylamide-n-butyl methacrylate） terpolymer as the modifier.The influences of modifier amount，modification time，modification temperature，and stirring speed on the modifying effect of GCC were investigated.Furthermore，the modifying effect was also evaluated by the indexes，such as sedimentation volume，oil absorbed value，viscosity，whiteness，contact angle，degree of activation，particle size，and morphology etc..Results showed the modifying effect of P（MA-BA-BMA） terpolymer was good. Through single factor and orthogonal experiments，the optimal modification conditions were obtained as follows：modifier amount was 2 %，modification temperature was 85 ℃，modification time was 120 min，and stirring speed was 500 r/min.

Key words: ground calcium carbonate powder, surface modification, maleic anhydride, acrylamide, n-butyl methacrylate