Abstract: Studies on characteristics of 9518 cyanate ester curing reaction were performed via differential scanning calorimetry (DSC) analysis, the curing process of stated resin was determined; Thermal stability, mechanical properties, fiber morphology and interface properties of T800 carbon fiber/9518 cyanate ester composites were analyzed via dynamic mechanical analysis (DMA) testing, mechanical property testing, metallography and SEM, respectively. The results show that, the curing reaction of 9518 cyanate ester has only one reaction exothermic peak, one of the reasonable curing processes for the resin is 130℃/0.5 h+160℃/0.5 h(pressure-enforcement and mold-closing)+200℃/2 h+230℃/2 h. The glass transition temperature of T800 carbon fiber/9518 cyanate ester composites is 255℃. In general, mechanical properties of T800 carbon/9518 cyanate ester composites at room temperature are 10% higher than that of T700 carbon fiber/9518 cyanate ester composites, wet mechanical properties conservation rate of stated composites at room temperature are more than 83%, and withhold more than 60% at 200℃.Cross-section of T800 carbon fiber appeares abnormal round shape and along the fiber has ditches on the surface, contributing a fine interface between T800 carbon fiber and 9518 cyanate ester resin.