The effect of thermal treatment on mechanical property and microstructure evolution in two-dimension of nanocrystal corundum abrasives has been investigated. The abrasives with and without presence of bond were calcined at different thermal treatment temperatures. The results indicated that thermal treatment conditions had obvious influence on crystal size and mechanical strength of corundum abrasives. Crystal size increased with increasing of the calcining temperature, and crystal growth of sample with presence of bond was more remarkable than that without presence of bond. And it was found that 950 degrees C is the critical temperature of abnormal crystal growth of corundum abrasives in the heated treatment conditions. Beyond this critical temperature, crystal size evidently increased while strength and wear resistance of abrasive decreased. In this case, the degradation of the abrasive in microstructure and strength should be important considerations for the preparation of ceramic corundum abrasive grinding tool. (C) 2009 Published by Elsevier Ltd.