A lead lithium (PbLi) loop named as DRAGON-V was constructed in China to test key technologies of material corrosion, thermal-hydraulics, safety issues, etc for PbLi blanket of fusion reactor. The concentric recuperator, one of the most important components, was used to recover the enthalpy in the loop. To design the concentric recuperator structure, the tangent angle theta between straight pipe and elbow as well as the bending radius R for U-type connecting elbow were analyzed, respectively. It was indicated that the elbow presented well thermal deformation-absorbing function and reduced the thermal stress. There was a little effect on the deformation and heat transfer for the variation of R and theta, but the stress intensity increased with bending radius R and decreased with tangent angle theta. The results showed that the stress intensity in the structure with theta = 5 degrees and R = 1.5D was smaller than the others. And the optimized structure was evaluated according to standard of Steel Pressure Vessel-Design by Analysis, the structural strength met the design requirement, and large margin was kept for engineering application.