Pleural invasion refers to the invasion of tumor cells into the pleura, and pleural invasion is a high-risk factor for recurrence and metastasis of lung cancer after surgery. There is a membrane on the surface of the lung called the visceral pleura, which is a natural barrier to prevent lung cancer from spreading to the chest cavity. Pleural invasion refers to tumor invasion beyond the elastic lamina of the visceral pleura, as well as invasion of the surface of the visceral pleura. The cancer usually invades the pleura by direct spread. Cancer cells located in the periphery of the lung can invade the visceral pleura, and implantation metastasis can also be formed when the cancer cells are dislodged into the pleural cavity, while cancer cells close to the mediastinal surface are also able to invade the mural pleura, the chest wall tissues, and mediastinal organs. When lung cancer invades into pleura, it is suggested that patients should seek medical treatment as early as possible and listen to professional doctor’s advice.