[Objective] The aim of this paper is to analyze the influencing factors on the partial necrosis of the posterior tibial artery perforator-plus fasciocutaneous flap. [Methods] We retrospectively reviewed the data of 59 patients with soft tissue defects reconstructed using the posterior tibial artery perforator-plus fasciocutaneous flap between September 2007 and September 2017. The efficacy of the flap was evaluated. The patient factors, surgeon factors and flap factors were compared between the survival flaps and the partial-necrosis flaps. [Results] There were 50 flaps（84.75%） surviving completely. Partial necrosis occurred in 9 (15.25%) flaps, of which remanent defects were covered successfully by secondary suture (n=1), skin grafting (n=3), or transferring other regional flaps (n=5). There were no significant differences in gender, age, soft tissue defect site, length and width of fascia pedicle, length of skin island, length-width ratio (LWR), location of top-edge, and location of pivot point of the flap between the survival group and the partial necrosis group (P>0.05). The width of the skin island and the length of the flap in the survival group were significantly smaller than those in the partial necrosis group (p＜0.05). The partial necrosis rate (0/18, 0.00%) of the flap with the width of skin island < 6 cm was less than that (9/41, 21.95%) with the width of skin island ≥ 6 cm, and the difference was statistically significant (p＜0.05). The results of multi-factor logistics regression analysis showed that the width of the skin island was an independent risk factor affecting the partial necrosis of the flap. [Conclusions] The posterior tibial artery perforator-plus fasciocutaneous flap can be effectively used to repair the small and medium area wounds of the lower and middle leg, ankle and foot. When the width of the skin island is more than 6 cm, the partial necrosis rate of the flap is significantly increased.