Carbon fiber reinforced carbon composites (C/Cs), are the most promising high-temperature materials and could be widely applied in aerospace and nucleation fields, owing to their superior performances. However, C/Cs are very susceptible to destructive oxidation and thus fail at elevated temperatures. Though matrix modification and coating technologies with Si-based and ultra-high temperature ceramics (UHTCs) are valid to enhance the oxidation/ablation resistance of C/Cs, it's not sufficient to satisfy the increasing practical applications, due to the inherent brittleness of ceramics, mismatch issues between coatings and C/C substrates, and the fact that carbonaceous matrices are easily prone to high-temperature oxidation. To effectively solve the aforementioned problems, micro/nano multiscale reinforcing strategies have been developed for C/Cs and/or the coatings over the past two decades, to fabricate C/Cs with high strength and excellent high-temperature stability. This review is to systematically summarize the most recent major and important advancements in some micro/nano multiscale strategies, including nanoparticles, nanowires, carbon nanotubes/fibers, whiskers, graphene, ceramic fibers and hybrid micro/nano structures, for C/Cs and/or the coatings, to achieve high-temperature oxidation/ablation-resistant C/Cs. Finally, this review is concluded with an outlook of major unsolved problems, challenges to be met and future research advice for C/Cs with excellent comprehensive mechanical-thermal performance. It's hoped that a better understanding of this review will be of high scientific and industrial interest, since it provides unusual and feasible new ideas to develop potential and practical C/Cs with improved high-temperature mechanical and oxidation/ablation-resistant properties.

National Natural Science Foundation of China (NSFC), Grant No. 91860203, 51821091, 51872239, 52002321, 52061135102. China Postdoctoral Science Foundation, Grant No. 2019M660265. Fundamental Research Funds for the Central Universities, Grant No. G2019KY05116, G2020KY05125. Innovation Talent Promotion Plan of Shaanxi Province for Science and Technology Innovation Team, Grant No. 2020TD-003. Creative Research Foundation of Science and Technology on Thermostructural Composite Materials Laboratory, Grant No. 614291102010517, 505020 0 015, 515020 0 033. Shaanxi Provincial Education Department of China, Grant No. 2020JQ-170