MCPA6 was synthesized by anion polymerization with ε-caprolactam as monomer, NaOH as initiator and toluene 2,4-diisocyanate as activator. The effects of initiator molar ratio and polymerization temperature on the synthesis of MCPA6 were discussed. The research results showed that as the initiator content increased, the monomer conversion rate showed a trend of first increasing and then slightly decreasing. When the molar ratio of initiator was 0.0044, the monomer conversion rate reached the highest value of 91.5%, with a crystallinity of 44.5%. The tensile strength of the sample was 83.6 MPa, the flexural strength was 112.4 MPa, and the impact strength was 5.3 kJ/m2. Within the studied temperature range, with the increase of polymerization temperature, the monomer conversion rate slightly increased, and the mechanical properties of the sample showed a trend of first increasing and then decreasing. The tensile strength and flexural strength reached their maximum values at 160 ℃, and the impact strength reached their maximum values at 170 ℃. Therefore, when the molar ratio of initiator was 0.0044 and the polymerization temperature was 160 ℃, MC nylon 6 showed good process stability. This synthesis method had certain application value.