A process of manufacturing a plastic product includes selecting natural or synthetic fiber as a material; adhering a thermoplastic resin onto surfaces of the material to form a thin film thereon by soaking or heating; heating the thin film; forming two releasable films on upper and lower surfaces of the thin film respectively; cutting the thin film into thin film units; heating and pressing the thin film units to form cured thin film units; applying one of the cured thin film units onto an inner surface of a first mold; further heating and pressing the cured thin film unit to form a thin film structure; placing the thin film structure inside a second mold; and injecting a thermoplastic material into the second mold to adhere onto an outer surface of the thin film structure to produce the finished plastic product.