Abstract: On the basis of DR (Digital Radiography)/CT security inspection system, DR/SSCT (single slice spiral CT) security inspection system was developed. This spiral CT system can improve the CT system’s drawbacks. The research work includes in replacing the former data acquisition system by a new system which can acquire projection data of multi-slices and devising the SSCT reconstruction algorithms. Simulation experiments and practical experiments were devised to contrast several algorithms. Interpolation technique was operated in detectors data in order to improve the algorithms. In conclusion, the system exploits an algorithm of weighted average of 360° LI (Linear Interpolation) and JH-HI (Jiang Hsieh-Half scan Interpolation).