Objective To investigate the clinical effect of self-made splint fixation in supination position in the treatment of extended distal radius fracture with distal radioulnar joint injury.Methods A total of 64 patients with extended distal radius fracture with distal radioulnar joint injury admitted to Guangzhou Integrated Traditional Chinese and Western Medicine Hospital from May 2016 to May 2019 were selected as the research objects,and they were divided into the plaster group and the splint group according to random number table method,with 32 cases in each group.The plaster group was fixed with long-arm plaster in supination position,and the splint group was fixed with self-made splint in supination position.The time to fracture healing,the total incidence of complications,the Garland-Werley wrist score and the incidence of radioulnar joint instability were compared between the two groups.Results There were no statistically significant differences in fracture healing time and the excellent and good rate of Garland-werley wrist score between the two groups(P＞0.05).The incidence of radioulnar joint instability in the splint group was lower than that of the plaster group,and the difference was statistically significant(P＜0.05).The total incidence of complications in the splint group was lower than that in the plaster group,and the difference was statistically significant(P＜0.05).Conclusion The self-made splint fixation in supination position is more conducive to maintaining the stability of the distal radioulnar joint.It has the advantages of simple operation,fewer complications,and good recovery of wrist joint function,which is more worthy of clinical promotion.