Objective To investigate the clinical effect of subcutaneous tissue pedicle rhomboid flap plasty in the treatment of scar contracture after burn. Methods A total of 100 patients with scar contracture after burn admitted to Handan Hangang Hospital from January 2020 to December 2021 were selected as the research objects. According to the random number table method, they were divided into observation group and control group, with 50 cases in each group. The control group was treated with conventional free skin graft transplantation, and the observation group was treated with subcutaneous tissue pedicle diamond flap plasty. The treatment satisfaction, wound healing time, flap survival rate, recurrence rate, complication rate and quality of life score were compared between the two groups. Results The total treatment satisfaction of the observation group was 98.00%, which was higher than 84.00% of the control group (P<0.05). The wound healing time of the observation group was shorter than that of the control group, the survival rate of the flap was higher than that of the control group, and the recurrence rate was lower than that of the control group (P<0.05). The incidence of complications in the observation group was 4.00%, which was lower than 20.00% in the control group (P<0.05). The quality of life scores of the two groups after treatment were higher than those of the control group (P<0.05). Conclusion Subcutaneous tissue pedicled rhomboid flap plasty has a good effect in the treatment of scar contracture after burn, which can effectively improve the survival rate of flap, shorten the time of flap pedicle breaking, reduce the infection rate of flap, effectively control the inflammatory reaction around the wound, improve limb function, improve skin repair, and promote rapid recovery of patients.