Abstract: CiADS subcritical reactor used LBE as coolant and closed fuel assembly mixed by wire wrapped. The wire can make the working fluid cross-mixing, enhancing the momentum exchange between coolant in different subchannel. This study generated structured and unstructured mesh by software ANSYS ICEM and STAR-CCM+, analyzed the cross-flow characteristics in CiADS subcritical reactor and investigated the influence caused by using different mesh structure in CFD simulation. The calculation result showed: comparing with unstructured mesh, the cross g between subchannel calculation in structured mesh is closer to the result in LES. The friction factor calculated by structured mesh is closest to the prediction of UCTD formula, and the factor calculated by unstructured mesh is smaller than all empirical formula. In addition, this research refined existed empirical formula, which could predict cross-flow characteristics more accurate. The conclusions provided a new way refining subchannel progress, and provide data support for thermohydraulic design and analysis in CiADS fuel assembly.