Abstract: Caprolactam was used as raw material, sodium caprolactam (C10) and diacyllactam-1,6-hexanediamine (C20) as initiators and activators respectively. The anionic polymerization process of nylon 6 (PA6) suitable for reaction injection molding (RIM) technology was explored. The results show that polymerization rate can be improved by increasing the concentration of C10, but the limiting viscosity number is the opposite. However, increasing the concentration of C20 alone results in incomplete polymerization and low conversion. With the increase of polymerization temperature, the degree of polymerization can be increased. Finally, the unidirectional carbon fiber (CF)/PA6 composites with good properties were prepared by selecting the technological parameters of C10 1.5 mol%, C20 1 mol%, dipping temperature of 100℃ and polymerization temperature of 180℃. The tensile strength along the fiber direction can reach 974.2 MPa, and the bending strength can reach 786.9 MPa.