Process for manufacturing composite material products (44, 48, 52), which process comprises at least the following operating steps: - moulding at least one main component (18) made of a composite material and one or more secondary components (19, 20, 21, 22) made of a composite material by means of one or more main moulds (11, 13) and one or more secondary moulds (23, 24, 25, 26), respectively; arranging one or more intermediate substrates (41) of fibers, in particular carbon fibers, pre-impregnated with a resin, between said main component (18) and / or said secondary components (19, 20, 21, 22) in a moulding assembly (40) comprising at least one main mould (11; 31) and / or one or more secondary moulds (23, 24, 25, 26; 35, 36, 37, 38, 39); curing the resin of said intermediate substrates (41) in the moulding assembly (40), so that the main component (18) and the secondary components (19, 20, 21, 22) are joined to each other through the intermediate substrates (41). The present invention also relates to a system which can be used in such process, as well as the products manufactured with this process and / or system.