For the verification of industrial CT detection sensitivity of micro-scale defects in metal additive manufacturing samples， an assembled structural specimen block， which includes a reference specimen， was designed and manufactured to evaluate detection performance in the target region of the part. Using the test block， the variation in defect detection sensitivity within its region of interest was preliminarily investigated under varying geometric magnifications and eccentricity distances. Results show that， with the reduction of the detection geometry magnification， and the increasing eccentricity distance， the size of the undetectable defects gradually increases， and the detectability of the defects and the accuracy of the identification gradually decreases.