The ultra-fine treatment of industrial SiC powder was carried out by fluidized bed opposed jet milling (QLM-100K), and the influences of grinding parameters on the ultra-fine treatment were studied. A better grinding result is achieved through a higher crushing pressure and a higher sorter frequency and the ultra-fine treated SiC powder possesses a smaller particle size, a narrower particle-size distribution, a higher specific surface area and reduced agglomeration. The effects of ultra-fine treatment on the compaction behaviors, sintering behaviors, properties and microstructure of SiC ceramics were investigated. The compact with ultra-fine treated powder has a higher density and a lower sintering temperature. The densification and mechanical properties of the ceramics can be ameliorated obviously and the microstructure defects of the ceramics decrease.