Objective To evaluate the prognostic factors in locally advanced non-small-cell lung cancer (LA-NSCLC) for selectively carrying out prophylactic cranial irradiation (PCI).Methods 114 patients with LA-NSCLC between Jun 2006 and Oct 2010 were retrospectively analyzed. Related risk factors and features about brain metastases were analyzed.Results The 2-year incidence rate of brain metastases was 31.58 ％ (36/114),the first brain metastases was 20.18 ％ (23/114),and sole brain metastases was 9.65 ％(11/114),respectively.Variables involved in the equation of binary logistic regression analysis were pathology (OR =5.892) and treatment mode(OR =2.888).The incidence rate of brain metastases in patients of non-squamous carcinoma and single treatment mode was higher than others (P ＜ 0.01) Model fitting is better (P ＞ 0.05).Overall accuracy rate of predicting brain metastases is 67.7 ％.The increased rate of lactate dehydrogenase in the patients with brain metastases or death was 17.54 ％, which was higher than that in the survival patients without brain metastases (P ＜ 0.01).At the same time,the station number and the number of mediastinal lymph node metastases were positively correlated (r =0.716, P ＜ 0.01).The incidence rate of brain metastases or mortality rate was higher in the adenocarcinoma cases than that in the squamous carcinoma cases (P ＜ 0.01,P ＜ 0.05),with more frequent occurrence of mediastinal metastases.The mean diameter of squamous carcinoma and adenocarcinoma were 5.8 cm and 3.9 cm, respectively (P ＜ 0.01).Conclusions The incidence rate of brain metastases was higher in patients with single treatment.Large primary tumors, high lactate dehydrogenase, non-squamous carcinoma, multiple stations, and multiple mediastinal lymph nodes metastases can be regarded as risk factors of brain metastases to perform PCI.