Objective To explore the effect of optimal timing of internal fixation on postoperative complications of multiple rib fractures. Methods A total of 31 cases of multiple rib fractures receiving internal fixation in our hospital from Mar. 2014 to Jul. 2016 were included in this study. According to the time from injury to internal fixation, the patients were divided into early operation group (≤ 72 h, n=17) and routine operation group (>72 h, n=14). The clinical data of the patients were compared between the two groups, including age, gender, body mass index (BMI), number of fractured ribs, incidence of comorbidity, incidence of postoperative complications and pain improvement rate. Results There were no significant differences in age, gender, BMI, number of fractured ribs, or incidence of comorbidity between the two groups (all P>0.05). The time from injury to internal fixation was significantly less in the early operation group than that in the routine operation group ([2.2±1.5] d vs[7.4±2.8] d, P<0.01). The ventilator-assisted ventilation time was significantly shorter in the early operation group than that in the routine operation group ([8.9±3.7] h vs[13.6±5.2] h, P=0.006). The incidence of pulmonary infection and postoperative atelectasis was significantly lower in the early operation group than that in the routine operation group (5.9%[1/17] vs 42.9%[6/14], P=0.028; 0.0% (0/17) vs 28.6%[4/14], P=0.032). The improvement of postoperative pain was 94.1%[16/17] and 78.6%[11/14] in the early and routine operation groups, respectively, and the difference was not significant (P>0.05). Conclusion Early internal fixation surgery (≤ 72 h) may contribute to reducing incidence of postoperative pulmonary infection and atelectasis of the patients with multiple rib fracture.