Abstract: Objective　To explore the anatomical characteristics of the semimembranosus popliteal perforators, providing morphological basis for the reconstruction of soft tissue defects around the knee joint. Methods　After 30 sides of adult lower extremity specimens were perfused with red latex,  the following contents were observed emphatically under a surgical magnifier：①The origin, courses, branches, and distribution of the nutrient vessels of the semimembranosus muscle. ②The anastomosis characteristics of semimembranosus popliteal perforators and adjacent perforators.　Results　The semimembranosus popliteal perforators, with an outer diameter of (0.7±0.3)mm and a length of (1.1±0.4)cm on average, commonly originated from the semimembranosus muscular branch at 13.5cm proximal to the tibial condyle, and then punctured out of the deep fascia towards the subcutaneous plane, and finally sent out numerous tiny vessels to form anastomosis with the direct cutaneous perforators of the popliteal artery as well as the medial popliteal cutaneous arteries.　Conclusions　The flap pedicled with the semimembranosus popliteal perforators could become a supplement for repairing the soft tissue defects around the knee joint in the form of transposition or V-Y advancement.

Key words: Semimembranosus muscle, 　Popliteal fossa, 　Perforator flap, 　Soft tissue defect