Abstract: The reactor core physical analysis of annular fuel is needed in order to investigate feasibility of annular fuel applied in the large commercial PWR. The reasons behind inaccurate results when using CASMO5 code were studied and the methods to deal with the problems were introduced. And the steady state core physics performance was analyzed with four groups of annular fuel leading test assembly loaded into the steady state reactor core of Qinshan Phase Nuclear Power Plant Ⅱ. According to the computed results, loading annular fuel leading test assembly has little influence on the steady state core physics performance, and it is feasible to do annular fuel reactor core physics performance calculation by CMS code package.