Abstract: Objective To investigate the motion of clinical target volume（CTV）by using cone beam computed tomography（CBCT）on linear accelerator and to determine a internal margin（IM）value for the internal target volume（ITV）during intensity-modulated radiotherapy（IMRT） for non-surgical cervical cancer. Methods One hundred and forty CBCT images from 20 non-surgical cervical cancer patients who underwent radical IMRT from Dec 2013 to Oct 2014 were selected for this study. The deformation and displacement between the simulation CT and CBCTs were measured. Results The volume reductions of CTV1 between the simulation CT and CBCTs were（33.56±22.52）cm3（range from 1.04-110.22 cm3）and the percentages of the volume reductions were（10.19±6.32）％（range from 0.37％-32.01％）. The motion between the simulation CT and CBCTs were（1.19±0.82）cm,（0.80±0.55）cm,（0.16±0.25）cm,（0.23±0.29）cm,（0.27±0.42）cm,（0.18±0.24）cm and（0.78±1.09）cm in the anterio-posterior directions of uterus，anterio-posterior directions of cervix，superior directions of uterus，lateral directions of the same side，the opposite side of the bottom of uterus，respectively. If the IM was set less than 2 cm，the CTV of 85％ CBCTs could be covered completely. 95％ patients showed greater uterus motions than cervical motions in all directions. The motion of CTV1 had great individual difference. Conclusion The strategies of target outline for different IM size at three dimensional direction obtained by CBCT and different IM size of uterus and cervix, in combination with individualized image guided radiotherapy may be a good clinical form for realizing precise radiotherapy in cervical cancer.