The flow field calculation of high temperature gas-cooled reactor (HTGR) core is an important part in HTGR simulation.The block iteration method was used in previous reactor core flow field simulation codes,but in some cases the convergence speed was very slow and convergence was hardly achieved.To improve this problem, the theory about convergence of block iteration method was investigated.Based on the idea of global solution,a highly efficient global solution method was developed for the calculation in the flow field of HTGR core.The direct solving method was employed in the new global solution method and it was based on the characteristics of the flow field model.Compared with the block iteration method,the effect and efficiency in convergence and calculation speed are significantly improved.