Pleural pulling, also clinically known as pleural depression sign, is usually considered to be caused by fibrous tissue proliferation, dirty layer pleural depression, and thickening of pleural adhesions. 1. Fibrous tissue hyperplasia: when there is chest infection and other causes pleural effusion for a long time, the internal structure of the lesion has fibrin deposits, which will easily cause fibrous tissue thickening and thus pleural pulling sensation. 2. Dirty layer pleural depression: when there is lung atelectasis and other diseases, the local pleura is wrinkled and collapsed, which is manifested as pleural depression. 3. Pleural thickening and adhesion: long-term inflammatory factors cause pleural adhesion and hyperplasia, the pleura of the dirty layer and the wall layer are adhered, thus increasing the friction of the airway during breathing, accompanied by respiratory pain. In conclusion, the cause of pleural pulling is more complicated, and malignant lesions are often considered to be the cause of the symptoms, which should be promptly consulted for a clear diagnosis.