Abstract: Ground calcium carbonate powder（GCC） was modified by wet ball milling method， using stearic acid（SA） and ti- tanate coupling agent（TCA） as composite modifier，and with ethanol as dispersant.The influences of ball-milling time，rotat- ing speed of ball-milling，modifier amounts，and mix ratios of modifiers on the modifying effect were investigated by single factor tests，using activation grade as evaluating index.Furthermore，the optimal modifying conditions were achieved by ortho- gonal experiment as follows：ball-milling time was 1.5 h，rotating speed of ball-milling was 350 r/min，modifier amount was 2.0%（mass fraction），and m（SA）:m（TCA）=1:3.The performances of the modified sample under these conditions were as fol- lows：activation grade was 99.4%，oil absorption value was 14.27 g per 100 g modified samples，sedimentation volume was 1.08 mL/g，and particle size D50 was 1.58 μm.

Key words: ground calcium carbonate, stearic acid, titanate coupling agent, wet ball milling method, activation grade