Abstract: An optimization conceptual design of CSR1000 core is proposed. Steady state performance of the proposed core is then studied with the SCWR core steady state analysis code system SNTA. These key parameters such as burnup performance, reactivity control capability, power distribution, maximum fuel cladding temperature and maximum linear power density are analyzed. The relative coolant flow rate of the second flow path which is suited with assembly power is also presented. The study shows that the life of CSR1000 core could be extended effectively with the optimization design for CSR1000 fuel assembly and core.