Abstract: Objective To investigate the relationship between bladder and rectum volume and its absorbed dose of radical intensity modulated radiotherapy(IMRT) on cervical cancer. Methods We selected 50 cervical cancer patients who received radical IMRT, told patients moderate bladder filling (drink 500-800ml water, 30-60minutes later to scan images), the rectum must be emptied before scanning the radiotherapy plan CT, analyzed the correlation of the bladder and rectum volume with each mean dose and V45. Results Bladder and rectum volume change was large, they had no significant correlation with each mean absorbed dose, V45 or D2cm 3, but there was a significant positive correlation between Vob/Vb, Vor/Vr and Dmb/Dp, Dmr/Dp, V45. We used the matlab software to analyze the correlation formula between Vob/Vb, Vor/Vr and Dmb/Dp, Dmr/Dp, V45. Conclusion The volume of bladder and rectum is large during the radiotherapy. We could use the correlation formula to predict the mean absorbed dose of bladder rectum and V45 before radiotherapy in individual patients, analyze the causes of excessive doses of the bladder and rectum, and rectify them immediately.