Objective To study the preparation process of siloxane-based polymer modified nano-Al2O3 suspension. Methods The nano-Al2O3 content in its suspension was used as the indicator to assess the effect of different modifiers, dosages of modifiers, modification time, and suspending solvents on the suspension. Results Optimal conditions for preparation process were determined as follows: dosage of modifiers 0. 010 mL/ g(Al2O3), modification time 30 min, and the suspension solvent was PMA. Under these conditions, the maximum content of nano-Al2O3 in its suspension was up to 0. 4915 g/ mL. Conclusion Siloxane-based polymer can modify nano-Al2O3 effectively by coating the surface,and modified nano-Al2O3 suspension is stable.