Abstract: To address the incompatibility, poor dispersion, poor fluidity, and easy agglomeration in the combination of magnesium oxide powders and organic matrix, the light-burned magnesium oxides were treated by mechanochemical synergistic organic modification method through mixing and ball milling. The effects of modifier type, modification time, and modifier amount on the microstructure, lipophilic degree, activation index, and liquid paraffin suspension viscosity of the magnesium oxides were studied. The results show that the organic modifying agents (sodium laurate, sodium stearate, and titanium acid ester coupling agent TCA-KTTT) can all effectively modify the powders, and the MgO powders modified by sodium stearate have the better comprehensive performance. The sodium stearate modified MgO powders are coated with crumbly substances, and the Fourier transform infrared spectrum analysis confirms the effective adsorption of straight-chain alkyl groups on the surface. Under the optimal conditions (the modifier is sodium stearate with the mass fraction of 7% and the modification time is 5 h), the magnesium oxide products exhibit the lipophilic degree of 36.1%, activation index of 96.4%, and paraffin suspension viscosity of 3270 mPa·s. Furthermore, the modified powders demonstrate the improved organic compatibility, compared to the unmodified powders.