Abstract: Objective To investigate the application value of detection of aspartic protease A(NapsinA), thyroid transcription factor-1(TTF-1), excision repair cross-complementing 1(ERCC1)expressions in lung cancer patients. Methods The pathological specimen of surgical resection for lung tumor from 40 patients in our hospital were selected, and adjacent normal tissues from 40 cases were taken as controls. The expressions of NapsinA, TTF-1 and FERCC1 were detected. Results The expression levels and positive rates of NapsinA, TTF-1 and ERCC1 in lung cancer tissues were higher than those in adjacent normal tissues(P<0.05); the positive rates of NapsinA expression in patients with different pathological types and differentiation degrees were statistically significant(P<0.05); the positive rate of TTF-1 expression in patients with different pathological types and TNM stages showed significant difference(P<0.05); there was no significant correlation among NapsinA, TTF-1, ERCC1(P>0.05). Conclusion The expression of NapsinA, TTF-1 and FERCC1 can be detected - to judge the condition of lung cancer.