Heat conductivity was examined for various fiber-reinforced composites and for its effects on the polymer matrix, a monotropic fiber-reinforced composite, and hybrid unidirectionally and spatially reinforced composites. The results of tests conducted on a unidirectional composite material were used to determine the heat conductivity of fibers, and the results of experiments carried out on a hybrid and spatially reinforced composite material verified the calculation model based on the method of orientation averaging.