Abstract: ObjectiveTo compare the dose distributions and dose-volume histograms (DVHs) in critical organs of three-dimensional conformal radiotherapy(3DCRT),7 fields radiotherapy(7FRT) and intensity modulated radiation therapy(IMRT) through the analysis of planning target volume(PTV) in gastric cancer treatment. MethodsFive patients with pathologically confirmed stage T3,T4 N0M0 gastric carcinoma who underwent radical gastrectomy were enrolled in our study. Dosimetry studies were carried out by three different treatment planning, such as 3DCRT, 7FRT or IMRT, in which each patient was prescribed a dose of 45Gy to 95％ of PTV.The parameters of isodose distributions line, dose-volume histogram(DVH), V95%, V110%,CI, HI, EI of target volume and the dose of related critical organs were investigated. ResultsIMRT showed best dose uniformity and conformity, EI than 3DCRT and 7FRT（P<0..05）, and there was no statistical difference between 3DCRT and 7FRT in CI and EI（P>0.05）. 3DCRT was superior to 7FRT in CI（P<0.05）.IMRT had advantage at sparing liver compared with 3DCRT and 7FRT（P<0.05）,7FRT showed better D1/3 of liver than 3DCRT（P<0.05）,but no difference between 3DCRT and 7FRT in Dmean of liver（P>0.05） was observed. 3DCRT had more increased Dmax of spinal cord than IMRT or 7FRT（P<0.05）, and 7FRT was superior to IMRT（P<0.05）.The dose exposed by the both kidneys was not significantly different among 3DCRT, 7FRT or IMRT. ConclusionPlans of IMRT were superior to 3DCRT and 7FRT,and 3DCRT plans were superior to 7FRT in CI and Dmax of spinal cord. 7FRT showed better D1/3 of liver than 3DCRT.IMRT would appear to be the favored technique for gastric cancer radiation for clinical therapy.