Disclosed is a process for manufacturing composite material products, having the following operating steps: molding at least one main component made of a composite material and one or more secondary components made of a composite material by means of one or more main molds and one or more secondary molds, respectively; arranging one or more intermediate substrates of fibers, in particular carbon fibers, pre-impregnated with a resin, between the main component and/or the secondary components in a molding assembly comprising at least one main mold and/or one or more secondary molds; curing the resin of the intermediate substrates in the molding assembly, so that the main component and the secondary components are joined to each other through the intermediate substrates. The present invention also relates to a system which can be used in such process.