PURPOSE: To form a stabilized dry fiber preform by arranging a polymeric binder to adjacent fabric plies and passing heated air streams through all of the fabric plies to melt the binder to integrally bond the fabric plies.

CONSTITUTION: A polymeric binder has a small particulate or the thin fibrous shape and the general dimension of particles is set so as to have a diameter of about 100-400 μm. The binder is pref. set to a concn. of about 5-60 g/m2 per a pair of adjacent fabric plies. A plane or the molding surface of a madrel 10 on which fabric plies are stacked is generally perforated and has a large number of perforations 12 or lattices and high temp. air used in the melting of a thermoplastic polymer can be easily passed through the fabric plies by the perforations 12. After the binder is melted by the action of high temp. air, indoor cold air is sucked through the fabric plies under vacuum to rapidly solidify the molten plastic binder. By rapidly solidifying the ply binder, the density of a preform is enhanced and the productivity thereof is enhanced.