The original core measurement system dedicated to instrument control in a certain early-stage nuclear power plant has poor stability and needs frequent testing and maintenance. Considering the economy, reliability, timeliness and other factors of system replacement, combined with the IAEA aging management concept, this paper adopts the domestic improvement and development of the computer channel coding module of the core nuclear measurement system, and tests the module on the simulation test platform. The results show that the module meets the technical specifications. It has the characteristics of stable performance, high precision and strong anti-interference ability. The aging management strategy adopted in a nuclear power plant provides a reference for other nuclear power plants to prolong life operation and aging management.