Abstract: Based on the design of dual-cooled annular fuel elements, relevant mathematical and physical models were established to calculate the flow distribution, temperature field distribution and distribution of radial maximum fuel temperature positions along the axial direction, and a thermal-hydraulic calculation code was developed. Three evaluation indexes were independently proposed to evaluate geometric designs of dual-cooled annular fuel elements, and the ranges of optimal element sizes were obtained. Calculation results show that the optimized dual-cooled annular fuel element presents good thermal-hydraulic performance. The optimized geometric sizes agree well with those obtained by Massachusetts Institute of Technology, which demonstrates the code reliability and accuracy.