Micro nodules in both lungs means that there is a high density of negative lungs less than 3 mm in diameter seen bilaterally on chest CT images. Micro nodules in both lungs may be benign or malignant lesions. 1. Benign lesions: Patients with microscopic nodules in both lungs, such as prolonged smoking or poor working and living environments, have long-term particle deposition or factors that lead to lung infections. Most people may not have clinical symptoms; a few may have specific infections such as tuberculosis, parasites, candida, etc., leading to the appearance of bilateral lung micronodules. 2. Malignant lesions: multifocal malignant tumors of both lungs or metastatic lung cancer may be found as microscopic nodules in both lungs. Primary malignant tumor of lungs may be asymptomatic in early stage or with mild chest pain and other uncomfortable symptoms; metastatic lung cancer has primary lesions and is mostly metastasized from primary malignant tumors, such as gastrointestinal, genitourinary, liver, thyroid, breast, bone, soft tissue, skin cancers and sarcomas, etc., which need to be clarified with relevant examinations after combining with symptoms. The severity of double lung micronodules is greater compared with single lung nodules, so it is recommended to consult a regular hospital for treatment as soon as possible.