The symptoms of postoperative thrombosis mainly refer to the formation of deep vein thrombosis in the lower extremities after surgery. Due to the different sites of deep vein thrombosis, the symptoms produced are also different. For deep vein thrombosis occurring in the calf, the swelling of the calf is not very serious, but the patient will feel very painful in the calf muscle when walking. When squeezing the calf muscles during the examination, for example, there will be pressure pain in the gastrocnemius muscle, which indicates that there is intermuscular thrombosis in the calf. If a thrombus is formed in the thigh, the swelling of the patient’s calf is very serious and will be aggravated when moving. Moreover, if the thrombus is dislodged, the size of the thrombus is relatively large and it will easily block the main trunk of the pulmonary artery, which will cause serious pulmonary embolism, and the patient will experience chest tightness, chest pain, hemoptysis and other occurrences, and in severe cases, the patient will have difficulty in breathing, which will endanger the patient’s life.