Microscopic nodules in both lungs refer to small nodules less than 5 mm, mostly chronic inflammatory nodules, which are benign changes without clinical manifestations and do not require special treatment, only dynamic follow-up of chest high-resolution CT once a year is needed. It is also necessary to ask the patient’s past medical history, whether there is a long-term history of smoking and dust work, such as masons, coal miners, etc., including a history of long-term exposure to other foreign bodies, such as chefs, hairdressers, tailors, chemical industry, etc. People in the above industries will be irritated by foreign substances for a long time and are prone to the formation of microscopic nodular changes in the lungs. Those with a history of pet ownership, including cats, dogs, ducks, geese, and pigeons, are also prone to the formation of microscopic nodules in both lungs. If there are autoimmune diseases such as rheumatoid or systemic lupus erythematosus, they are also prone to form tiny nodules in both lungs. If pathological puncture is performed on the nodules, it is mostly suggestive of inflammatory granulomatous changes. In conclusion, microscopic nodules in both lungs are pulmonary manifestations caused by chronic infections, tuberculosis infections, and autoimmune diseases. A high-resolution CT of the chest and, if necessary, a percutaneous lung puncture cytologic biopsy are required to further clarify the diagnosis.