Objective:To investigate the ability of bioluminescence imaging (BLI)used for early detection of lung tumors and quantitative measurement of tumor size. Methods:The luciferase activity of SPC-A1-luc cell was detected in vitro by BLI. SPC-A1-luc cells were subcutaneously injected into nude mice to establish mice subcutaneous tumor model,and the subcutaneous tumor was imaged every week by BLI and measured by caliper. SPC-A1-luc cells were intravenously injected into nude mice to establish intrapulmonary micrometastases model,BLI and micro-CT were used to monitor tumor growth and quantitatively analyze tumor size. Results:SPC-A1-luc cells stably and highly expressed luciferase,and the luciferase activity was significantly correlated with cell numbers(R2=0.9966)and tumor volume(R2=0.9849). Bioluminescence signals were diffused distribution in bilateral lung at the first week. On the third week,quantitative analysis showed that bioluminescence signals were the lowest and approximately 600 tumor cells were growing in the lungs. However,intrapulmonary micrometastases could not be detected by micro-CT until the 6th week, it was three weeks later than BLI. Conclusion:Intrapulmonary micrometastases could be early detected and quantitatively analyzed by BLI,which has higher sensitivity than micro-CT.