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Objective To evaluate the results of orthodontic micro- implant anchorage implantation by application of Spiral CT and three-dimensional reconstruction techniques, so as to explore its application value in assisting clinical diagnosis and treatment. Methods 20 orthodontic patients were implanted with 48 micro- planting screws. SOMATOM Sensation 40/64 helical CT scan was performed. The axial unenhanced helical CT data were given multi-planar reconstruction (MPR), maximum intensity projection (MIP), volume rendering (VR) and surface multidimensional reconstruction (CPR) by using the Siemens 3D post-processing software. The axial scanning images and reconstructed images were compared, observed and analyzed . Results The planting results of 37 micro screws were satisfactory without injuring the vital tissues surrounding the root. The planting results of 11 micro-screw were not ideal, and these micro-screws were observed or reimplanted and got success. Spiral CT axial scan showed better the tooth root interval and the relationship between tooth root and the planting screws. VR can directly showed the overall relationship between the planting screws and teeth, jaw contour appearance. The relationship between the screw and tooth was showed satisfactorily by MIP which could rotate freely and observe from different angles. MPR could clearly show the structural relationships between micro-root planting screws and tooth root and surrounding tissues from the cross section, and could make up for the shortcomings of axial limitations, and was easy to measure the distance and tilt angle of the long axis. Conclusion Spiral CT and three-dimensional reconstruction can accurately show the jaw micro planting screw shape, location and spatial relationships with adjacent teeth, the image is clear, intuitive and definite, and spiral CT and three-dimensional reconstruction has high application value in orthodontics micro-implant anchorage clinic as a powerful auxiliary examination means. [ABSTRACT FROM AUTHOR]