Objective To compare the effects of immediate postoperative injection of different doses of botulinum toxin type A (BTXA) on scar hyperplasia after facial surgery. Methods A total of 68 patients who underwent facial surgery in Fujian Medical University Union Hospital from January 2023 to December 2024 were selected. According to the random number table method, they were divided into the control group and the observation group, with 34 patients in each group. The control group received immediate postoperative injection of low-dose BTXA (4 U per point), and the observation group received immediate postoperative injection of higher-dose BTXA (8 U per point). The clinical efffcacy, scar hyperplasia and complications were compared between the two groups. Results The total effective rate of the observation group (94.12%) was higher than that of the control group (85.29%) (P<0.05). At 3 and 6 months after surgery, the scores of scar width, incision line and total mSBSES score in the observation group were better than those in the control group (P<0.05). There were no statistically signiffcant differences in the scores of scar thickness and color between the two groups (P>0.05). The incidence of complications in the observation group (11.76%) was lower than that in the control group (35.29%) (P<0.05). Conclusion Immediate postoperative injection of higher-dose BTXA is more effective than low-dose BTXA in improving incision scar hyperplasia after facial surgery, and it is conducive to reducing the incidence of complications, with good safety.