Objective To explore the clinical efficacy of 3 D printing technology-assisted external fixation frame in the treatment of long-bone diaphyseal fractures.Methods One hundred and twenty patients with long-bone di-aphyseal fractures admitted to a hospital in Liaoning province from July 2017 to July 2020 were selected for the study and divided into a control group（n= 58） and an observation group（n= 62） using the random number ta-ble method.Patients in the control group were given traditional surgical treatment and patients in the observation group were given 3 D printing technology-assisted external fixation frame treatment

and the perioperative inde-xes

treatment excellence rate

limb movement function and complications occurred in the two groups were com-pared.Results The observation group had shorter operation time

healing time and hospitalization time than the control group

and less intraoperative bleeding than the control group

and the differences were statistically sig-nificant（P<0.05）.The treatment excellence rate of patients in the observation group was 95.16%

which was higher than that of the control group（77.59%）

and the difference was statistically significant（χ~2= 8.010

P=0.005）.The fugl-meyer assessment（FMA） scores of patients in both groups were higher after treatment than before treatment

and the observation group was higher than the control group

and the difference was sta-tistically significant（P<0.05）.The complication rate of patients in the observation group was 8.06%

which was lower than that of 22.41% in the control group

and the difference was statistically significant（χ~2= 4.839

P=0.028）.Conclusion 3 D printing technology-assisted external fixation frame is effective in treating long-bone diaphyseal fractures

which helps to shorten the operation time

reduce intraoperative bleeding and complica-tions

and improve limb function

and is worthy of clinical promotion and application.