PET-CT examination can provide a more accurate diagnostic basis for lung cancer metastasis, but it does not guarantee the accuracy of the examination results 100%. PET-CT examination is an examination integrating PET technology and CT technology, which is relatively accurate among the existing malignant tumors and has a very high accuracy rate. PET-CT examination is able to visualize the whole body and can detect metastasis of lung cancer. PET carries out examination through nuclide labeling of glucose, if there are local inflammation and infection in the body, it will affect the metabolism of glucose in the body, which will then interfere with the examination and affect the examination result. As a result, the metastasis of lung cancer cannot be detected accurately. It is suggested that patients should keep a good attitude and actively cooperate with doctors to improve relevant examinations, make clear diagnosis and take targeted treatment measures.