Objective: To compare the results of quantitative analysis of cytology and DNA of bronchoscope brush and alveolar lavage, and to explore the application value of quantitative analysis of cellular DNA in bronchoscope brush and alveolar lavage. Methods: A total of 368 cases of bronchoscopy and alveolar lavage were selected, and the results were compared with pathological biopsy. Results: The sensitivity and specificity of the quantitative analysis of cellular DNA were 90.8% and 79.8% in bronchoscopy brush fluid, and 85.8% and 78.9% in alveolar lavage fluid, respectively. The sensitivity and specificity of liquid-based cytology in bronchoscopy examination were 68.1% and 63.4% in bronchoscopy brush fluid, and 65.9% and 60.8% in alveolar lavage fluid, respectively, in alveolar lavage. The sensitivity and specificity of the quantitative detection of cellular DNA by bronchoscopy and alveolar lavage were higher than that of liquid-based cytology (P<0.01). The positive predictive values of the quantitative analysis of cellular DNA in bronchoscopy and alveolar lavage were 83.5% and 82.4%, respectively. Conclusion: The quantitative analysis of cell DNA has a good application value in bronchoscope brush and alveolar lavage fluid, and the combination of liquid-based cytology can improve the detection rate of malignant tumors and reduce the risk of missed diagnosis and misdiagnosis.