The friction and wear behavior of Si3N4, SiC and ZrO2 sliding against M50 bearing steel under vacuum condition at various applied load were investigated. The results showed that the properties of different ceramic materials cause the difference in wear behaviors. The coefficient of friction was lowest in SiC and M50 bearing steel couple than other cases for graphitic carbon replaced carbidic carbon at the worn layer of SiC. The specific wear rate of ZrO2 was highest and the lowest was Si3N4. The ceramic ball materials have transferred on M50 bearing steel surfaces and tribofilm consistently formed on the ceramic balls wearing surfaces. Dominant wear behaviors for three structural ceramics were adhesion abrasion, plastic deformation and brittle fracture. The couple with Si3N4 and M50 showed the best operating conditions for friction and wear resistance under higher applied load.