Objective To explore the effect of modified Twin-block appliance in adolescent patients with skeletal class Ⅱ malocclusion. Methods A total of 90 adolescent patients with skeletal class Ⅱ malocclusion admitted to the Department of Stomatology, the People's Hospital of Jingbian from January to December 2024 were selected, and they were divided into the control group and the study group by the random number table method, with 45 patients in each group. The control group was given traditional Twin-block appliance, and the study group was given modified Twin-block appliance. The orthodontic effect, temporomandibular joint space indexes, hard tissue indexes and tooth comfort were compared between the two groups. Results The total effective rate of treatment of the study group (97.78%) was higher than that of the control group (82.22%) (P<0.05). The posterior temporomandibular joint space and superior joint space of the study group were higher than those of the control group (P<0.05). There were no significant differences in anterior joint space and lateral joint space between the two groups (P>0.05). The UI-NA, UI-NA angle, L1-NB and L1-NB angle of the study group were better than those of the control group (P<0.05). The total tooth comfort rate of the study group (93.33%) was higher than that of the control group (77.78%) (P<0.05). Conclusion The modified Twin-block appliance has a definite effect in adolescent patients with skeletal class Ⅱ malocclusion. It can improve temporomandibular joint space indexes and hard tissue indexes, and is conducive to enhancing tooth comfort, which is worthy of clinical application.