Objective To compare the clinical efficacy of mixed bone grafting and granular bone grafting in the treatment of nonunion after middle and lower tibial fractures. Methods 48 cases of aseptic bone nonunion in middle and lower tibia treated from May 2013 to May 2020 were retrospectively analyzed. According to the resultsof preoperative doctor-patient communication, 28 cases were treated with mixed bone grafting, and 20 cases were treated with particle bone grafting. The data of the two groups were collected, and the perioperative period, follow-up, imaging and other related indicators were compared. Results No important blood vessel or nerve injury occurred in the two groups, and the operation was successfully completed. The operation time and total incision length in the mixed bone grafting group were longer than those in the granular bone grafting group, and the differences were statistically significant (P<0.05); There were no significant differences in intraoperative blood loss, postoperative drainage volume, wound healing degree and total hospital stay (P>0.05). The walking time and full weight bearing activity time of mixed bone grafting group were significantly earlier than those of granule group (P<0.05). There was no significant difference in AOFAS score and ankle dorsiflexion/plantar flexion ROM between the two groups before surgery (P>0.05); At 3 months and last follow-up, the AOFAS score and ankle dorsalflexion ROM in the mixed bone grafting group were significantly higher than those in the granule group (P<0.05). In terms of imaging, the healing time of mixed bone grafting group was significantly earlier than that of granule group (P<0.05). At last follow-up, the Paley functional recovery score, Paley fracture healing score and Johner-Wruh score of the mixed bone graft group were better than those of the granule group (P<0.05). Conclusion Both implants can effectively treat the middle and lower tibial nonunion. In contrast, the clinical efficacy of mixed bone grafting is better than that of granular bone grafting.