The　authors　put　forward　an　automatic　segmentation　algorithm　for　tomographic　images　based　on　the　combination　of　object　detecting　and　region　growing　algorithms.　The　relation　graph　and　correlation　degree　are　firstly　defined　by　the　strict　rules　based　on　the　continuity　of　the　object　to　be　segmented　between　two　sequential　images.　Then　several　useful　shape　parameters　of　the　object　in　the　previous　segmented　image　and　relation　graph,　including　the　center　and　the　least　surrounding　boxes,　are　obtained　by　object　detecting　algorithm.　Finally　effective　seed　points,　which　are　generated　according　to　the　correlation　degree,　is　used　to　initialize　the　parameters　of　region　growing　algorithm　for　the　latter　slice.　The　experimental　results　show　that　the　new　algorithm　can　automatically　segment　serial　images,　and　improve　efficiency　by　a　factor　of　about　50%　compared　to　the　algorithm　of　voxel-based　region　growing.