Solid lung nodules are not always malignant, there are more causes of solid lung nodules, but most of them are benign nodules and a few are malignant, such as lung cancer. Solid nodules in the lungs are lung nodules with a solid component, and the main causes are: Infectious diseases such as tuberculosis ball, pneumonia, and lung abscess; Immune system diseases such as rheumatoid lung nodules; Pulmonary vascular diseases such as pulmonary hemangioma; Benign tumors such as pulmonary malignant tumors; malignant tumors such as lung cancer. Most solid nodules in the lungs are benign and fewer are malignant, but the nature of the nodules cannot be determined by imaging. As long as solid nodules are found in the lungs, enhanced CT examination or fiberoptic biopsy should be further improved to clarify the nature of the nodules as early as possible and treat them aggressively.