Multiple nodules in both lungs are mostly seen in malignant lesions of pulmonary metastases, but also in benign lesions such as cornual tuberculosis, necrotizing granuloma, multiple fluid-containing pulmonary cysts, and so on. 1. Lung metastatic tumor: it is often multiple, of different sizes, more frequent in the middle and lower fields of the lungs, with uniform or uneven density and clear margins. 2. Corn-grain type tuberculosis: multiple corn-grain nodular shadows in both lungs; acute corn-grain type tuberculosis nodules have the characteristics of uniform size, density and distribution; subacute and chronic corn-grain type tuberculosis nodules have the characteristics of uneven size, density and distribution. 3. Necrotizing granuloma: it is an inflammatory and proliferative lesion in the lungs, which is manifested as a solid nodular shadow on imaging. 4. Multiple fluid-containing pulmonary cysts: due to partial bronchial stenosis or atresia, the mucus can not be discharged and become. Most of them are enlarged by the fusion of terminal fine bronchioles or fine bronchioles, the size of the cysts varies, the number is variable, and the lungs are honeycombed in severe cases. Those who have multiple nodules in both lungs should go to regular hospitals in time for clear diagnosis and standardized treatment.