Abstract: Cyanate ester-epoxy resin(CE75) with 75% cyanate ester's mass fraction and high modulus carbon fiber reinforced CE75 resin (CF/CE75) composites were prepared. The processing property, cure schedule, thermal stability and mechanical properties of CE75 resin were studied. Furthermore, high modulus CF/CE75 composites were treated in simulated space environment, and then the mechanical properties and outgassing properties were investigated. The results show that CE75 resin possesses excellent processing properties, which are suitable for wet winding molding. The glass transition temperature and the initial decrease temperature of storage modulus of the CE75 resin are 195.6℃ and 368.6℃, respectively, indicating that the CE75 resin has good thermal properties. High modulus CF/CE75 pipes also presents excellent space-environment-resistant properties. After being exposed to vacuum condition, the outgassing behavior of the composites achieves the international standards. The results of thermal cycling test (-196-130℃) shows that the mechanical properties of pipes remain more than 96% after 200 cycles. Therefore, high modulus CF/CE75 composites will be a potential ideal candidate for the space-environment-resistant composites.