Objective: To observe the effect of 4-week preoperative resistance training on knee function, gait and quality of life in patients after medial open wedge osteotomy. Methods: A total of 60 patients who were going to undergo medial open wedge osteotomy from June 2020 to May 2022 were selected. In the enrolled 58 patients, 30 cases served as the rehabilitation education group and 28 as resistance training group by the random number table method. The rehabilitation education group received rehabilitation education before surgery, and the resistance training group underwent 4 weeks of preoperative resistance training. The knee function of the American Hospital of Special Surgery (HHS) was used to assess the knee function of the patient before training. After the preoperative training and 6 months after surgery, the quality of life was assessed by the World Health Organization Quality of Life Rating Scale (QOL-BRER). The step length, pace of the patient and cadence were assessed when completing a 20-meter walk on flat ground by wearing a portable gait evaluator. A handheld ergometer was used to measure the strength of the patient’s quadriceps and hamstrings. Results: There were no significant significances in HSS score, QOL-BRER score, step length, stride speed and cadence frequency between two groups before training. In the resistance training group, HSS score, QOL-BRER score, stride speed and cadence increased after preoperative training as compared with those before training (P<0.05), but there was no significant difference in the stride length before and after training. HSS score, QOL-BRER score, step length, stride speed, and cadence increased significantly at 6th month after surgery (P<0.05) as compared with those after preoperative training. In the rehabilitation education group, HSS score, QOL-BRER score, step length, stride speed, and cadence showed no no significant difference from those before education (P>0.05). HSS score, QOL-BRER score, step length, stride speed, and cadence frequency increased at 6th month after surgery as compared with those after preoperative education (P<0.05). As compared with the rehabilitation education group, the HSS score, QOL-BRER score, step length, stride speed and cadence frequency in the resistance training group increased after preoperative training (P<0.05). HSS score, QOL-BRER score, step length, stride speed, and cadence frequency increased at 6th month after surgery (P<0.05). The strength of the quadriceps muscle after preoperative training increased as compared with that before training (P<0.05), and the strength of the quadriceps muscle decreased after 6 months after preoperative training (P<0.05). The strength of the hamstrings after preoperative training increased as compared with the preoperative training (P<0.05), and the hamstrings at 6 months after surgery showed no significant difference from those after preoperative training (P>0.05). Conclusion: Preoperative resistance training can significantly improve knee function, gait, quality of life and muscle strength in patients undergoing medial open wedge osteotomy. High-intensity isokinetic reciprocal contraction training to strengthen the quadriceps and hamstrings muscles is performed before surgery, and the therapeutic effect has a certain consistent effect.