Y
2O
3 stabilized ZrO
2 toughened nanometer Al
2O
3,μmAl
2O
3 ceramic composites are obtained with a high-shear two-roll mill process.Their structure and mechanical properties are studied respectively.Further more,the microstructure of these ceramic composites was designed through mixing three grain-size powders.A fine ceramic composites of ZrO
2/nmAl
2O
3/μmAl
2O
3 is obtained.This ceramic composites can be densified above 98% of theoretical at 1550℃.Its flexual strengh and toughness are fine.