Objective To observe the effect of autologous fat injection for buttock augmentation under B-mode ultrasound assisted guidance on lipofilling survival rate. Methods Totally 100 patients who underwent buttock augmentation in Xiangmeihui Xiexi Medical Beauty Clinic from May 2022 to April 2024 were selected as the research subjects, and they were divided into control group and observation group according to the random number table method, with 50 patients in each group. The control group was treated with prosthesis buttock augmentation, and the observation group was treated with autologous fat injection buttock augmentation under B-mode ultrasound assisted guidance. The lipofilling survival rate, operation time, satisfaction and complications were compared between the two groups. Results The survival rate of lipofilling in the observation group after treatment was (70.49±2.02)%, which was higher than (55.67±3.12)% in the control group, and the operation time was shorter than that in the control group (P <0.05). The satisfaction rate in the observation group was higher than that in the control group (P <0.05). The incidence of complications in the observation group was 2.00%, which was lower than 14.00% in the control group (P <0.05). Conclusion Autologous fat injection for buttock augmentation under B-mode ultrasound assisted guidance can effectively improve the lipofilling survival rate, shorten the operation time, improve patients' satisfaction and reduce the incidence of complications, which is worthy of clinical application.