陶瓷材料具有高硬度、耐磨、耐腐蚀及耐高温等特点，但其脆性问题始终困绕着人们。近年来的研究发现，当陶瓷材料的晶粒变得很细小（处在纳米量级）时，其强度和断裂韧性均有很大程度提高。本文研究了纳米Ａｌ＿２Ｏ＿３粉的制备及其成型、烧结，研究了用纳米粉Ａｌ_２Ｏ_３烧制成的纳米晶Ａｌ_２Ｏ_３基复合陶瓷的断裂韧性与其晶粒尺寸间的关系。通过研究认为，细化陶瓷材料的晶粒也是解决其脆性，提高其断裂韧性的一条有效途径。 Ceramic materials with high hardness, wear resistance, corrosion resistance and high temperature characteristics, but its brittleness has always been trapped around the people. Recent studies have found that the strength and fracture toughness of ceramic materials increase to a great extent when the grains of the ceramic material become very small (on the order of nanometers). In this paper, the preparation of nano-Al_2O_3 powder and its formation and sintering were studied. The relationship between the fracture toughness and the grain size of nano-Al_2O_3 -based composite ceramics fired with nano-powder Al_2O_3 was studied. Through the study, the refinement of ceramic grains is also an effective way to solve the brittleness and improve the fracture toughness.