Abstract: Objective: To investigate the effect of tumor marker of lung cancer in the diagnosis of lung cancer, to find the best tumor marker so as to improve the diagnosis level of lung cancer. Methods: Ninety cases of lung cancer and 86 healthy subjects were recruited randomly for the study and 29 kinds of tumor marker in their peripheral blood were tested respectively. According to the detected results of every tumor marker we calculated the specificity, positive predictive value, sensitivity, negative predictive value, total effective rate and the mean of the five value. Results: According to their sensitivity and the mean of the five value, 29 kinds of tumor markers were sorted, the tumor markers with higher sensitivity and mean of the five value were selected as the best tumor marker. From those with higher means of five value, including PU、SA# CEA# CU-P、CA -242# CYFRA etc, the combination of CEA、SA and CA -242 were selected, whose sensitivity is up to 89.29%. Conclusion: The combination of PU、SA、CEA and CA-242 etc may be the best tumor marker in the early diagnosis of lung cancer.