Abstract: ObjectiveTo investigate the influence of two different prone positions with belly-board on target motions and their dose distributions in pelvic 3-Dimension intensity-modulated radiation radiotherapy of cervical cancer. Methods The motion ranges of GTV under two different prone positions with belly-board (The first prone position： the lower end of belly-board hole opening near the upper end of lumbosacral junction；the second prone position： the lower end of belly-board hole opening near the lower end of the sacroiliac joints) and the dose-volume histograms of GTV, CTV and PTVwere measured for all 10 cervical cancer patients received pelvic radiotherapy, and the relationship of them was compared. ResultsThe target motions under two different prone positions with belly-board are existed in the abdomen-back' directions (1~1.5cm),and have statistical significance (P<0.05),while there is no statistical significance in the head-feet' directions and left-right' directions(P>0.05)；But the dose-volume histogram changes of GTV, CTV and PTV under two different prone positions with belly-board are no Statistical significance(P>0.05). Conclusion The target motions under two different prone positions with belly-board are existed， but they have no influence on dose -volume histograms of themselves.