purpose To compare the dosage of target regions and bone in three-dimensional(3D)brachytherapy and two-dimensional(2D)Paris system brachytherapy for soft tissue sarcomas.Methods The brachytherapy was performed in total 18 soft tissue sarcomas patients who received the surgery with catheter insertion.The plans of 3D brachytherapy and 2D Paris system brachytherapy was designed in every patient respectively.The dosages differences of target regions and bone in patients and the distance between them were analysised between the two brachytherapy plans.Results There was no significant difference of target regions CTV-D100 between two brachytherapy techniques.The target regions CTV-D90 in 3D brachytherapy was much higher than 2D Paris system brachytherapy(P<0.05).The max dose D2cc in bone between two brachytherapy techniques are almost the same when the distance between the CTV and bone are farther(>8mm);but when they are near,max dose D2cc of the 3D brachytherapy is significant lower than 2D in bone.Only 38.9%plans of 2D Paris system brachytherapy and all 3D brachytherapy but one could achieved the requirement of clinical prescription dose of 400cGy*10 for CTVD90 and D2cc<5%for bone.The catheter insertion of that one is not good.Conclusions The 3D brachytherapy for soft tissue sarcomas could optimize the target coverage and reduce the dosages of bone(when distance>8mm)compared with 2D Paris system brachytherapy.The dosages of target regions and bone in both two brachytherapy techniques are maybe affect by the Catheter insertion,so the research should be undergo.