Objective To analyze the effection of improved three-dimensional conformal radiotherapy (3D-CRT) to the dose of target area of local advanced non-small-cell lung cancer (NSCLC) and observe the therapeutic efficacy and toxity.Methods 81 patients with local advanced NSCLC were collected and treated.The diameter of tumor exceed 5 cm.52 patients were squamous carcinoma.24 patients were adencarcinoma.5 patients were adenosquamous carcinoma.63 patients were onstage of Ⅲ A,18 patients were Ⅲ B.The patients were randomized into two groups,the first group was unmodified planning of 3D-CRT group (T1 group,39 patients),the second group was modified planning of 3D-CRT group (T2 group,42 patients).The 31 patients of T1 group (79.5 ％) received radiotherapy and chemotherapy.Toties quoties was 2 Gy.The fractions were 26-30.The total dose was 52-60 Gy.The 31 patients of T1 group (73.8 ％) received radiotherapy and chemotherapy.Toties quoties was 2 Gy.The fractions were 30-35.The total dose was 60-70 Gy.Results The 1-,2-,3-year overall survive rates of T1 group were 56.4 ％,33.3 ％,28.4 ％,the 1-,2-,3-year local control survive rates were 38.4 ％,28.2 ％,20.5 ％,and the median survive time was 17 months.The 1-,2-,3-year overall survive rates of T2 group were 61.9 ％,35.7 ％,28.5 ％,the 1-,2-,3-year local control survive rates were 47.6 ％,40.4 ％,30.9 ％,and the median survive time was 19 months.The significant difference was found for the local control survive rates between T1 and T2 group (P ＜ 0.05).No significant difference was found for the overall survive rates and the median survive time between T1 and T2 group (P ＞ 0.05).Conclution Improved 3D-CRT can advance local control survive rate and living quality to local advanced NSCLC.Meanwhile,it also increases survive rate of 1-year,but can not increase long-time survival rate.