Abstract: This paper presents simulation studies on eddy current signals resulted from wear and crack in control rod of nuclear reactor using CIVA. The results show that:the amplitude and phase of eddy current signal can be linearly related to the cross section loss and defect depth, thus they can be used in the quantitative characterization of defect. The proposed defect-amplitude-phase map may become an important indicator for defect type determination. The study provides reference for defect evaluation in the eddy current testing of control rod.