Speckled shadows in the lungs are not necessarily lung cancer, but to rule out the diagnosis of lung cancer, speckled shadows in the lungs can be seen in tuberculosis, common bacterial infections, fungal infections or metastases, so speckled shadows in the lungs need further differentiation. If it is accompanied by cough, yellow sputum and fever, it is most likely to be a bacterial infection, while the speckled shadow in both upper lungs with pleural effusion and pleural thickening is most likely to be caused by tuberculosis infection, while fungal infection often appears cavity-like changes on the basis of speckled shadow in lung, which will dissipate and absorb obviously through antifungal treatment. The spots of lung cancer are mainly of high density with irregular edges and short burrs at the same time. The specific pathological nature should be determined by microscopic examination after puncture biopsy, if cancer cells can be found, the diagnosis of lung cancer can be confirmed, if caseous necrosis is found, it is tuberculosis change, and if antacid bacilli are found, the diagnosis of tuberculosis can be confirmed.