Abstract: Purpose : To study the CT application value on conformable radiotherapy. Material and Methods : 47 tumor patients were cured with conformable radiotherapy. Their CT images before therapy were compared and analyzed with the CT images after therapy. Results : CT can define the size, position, adjoining relation and orientation marking of tumor before clinic therapy. After radiotherapy, CT can display the change of tumor size, location and the complication's degree. Conclusion : CT examination has very important application value on tumor location, therapeutic evaluation and complication evaluation in conformable radiotherapy.