Abstract: A core power distribution reconstruction method which attributes power deviation to assembly equivalence cross-section deviation was proposed. Through the analysis of the various factors that affect the core power distribution and modeling, the cross-section deviation and construct power deviation were introduced. Then, the original problem as an optimizing search problem was regarded. At last, the factors by characteristic statistic algorithm (CSA) were searched and replicated. To verify the feasibility of this method, xenon poison and moderator temperature field were chosen as factors in unit 2 reactor of Qinshan No.2 Nuclear Power Plant. The results show that this method is suitable for power distribution reconstruction preliminarily.