The invention discloses a process for producing a protein composite fiber, which consists of three parts, namely a stock solution process step, a spinning process step, and a secondary post-treatment and drying process step, wherein the stock solution process step comprises the key processes of skin selection, crushing, plasticization, desalination and acid decomposition; the spinning process step comprises the key processes of filtration and deaeration, maturation, spinning, post-treatment reaction, and water washing; and the secondary post-treatment and drying process step comprises the key processes of secondary post-treatment, vibration water washing, oiling, drying, packaging and loading and transporting. The collagen composite wig fiber produced by the process has the following advantages: firstly, the physical properties of strength, modulus and the like of the composite fiber are improved; and secondly, through the design of a specific fiber section and the compounding of different materials, and by using nanotechnology and fiber surface grafting and the like, the composite fiber is made into fibers with various forms and structures, and is endowed with special functions of fire retardance, static electricity resistance, antibacterial property, heat storage and heat preservation and the like so as to achieve the effects of emulation and over-genuineness. The process for producing the protein composite fiber fills up the domestic blanks, expands the market demands, and drives the development of related industries.