Objective To explore the effectiveness of mini external fixation device for comminuted open fractures of the metacarpal and phalange. Methods Between October 2009 and April 2011, 33 patients with comminuted open fractures of the metacarpal and phalange were treated with mini external fixation device. There were 25 males and 8 females, aged from 21 to 62 years with an average of 25.5 years. Of 33 cases, 7 were rated as Gustilo type II and 26 as Gustilo type IIIA; 20 cases were diagnosed as having simple metacarpal and phalangeal comminuted fractures and 13 cases as having combined interphalangeal or metacarpophalangeal joint fractures. Partial or complete rupture of tendon was observed in 18 cases. The time between injury and operation was 2-8 hours (mean, 3.7 hours). After one stage debridement and reduction, fracture was fixed with mini external fixation device. Results Primary healing of incision was obtained in 30 cases and no pin hole infection was found. Incision infection occurred in 3 cases and leaded to nonunion. Nonunion also occured in 2 cases of simple metacarpal and phalangeal fractures. The mean follow-up was 8 months (range, 6 months to 1 year). X-ray films showed fracture healing in 13 cases after 8 weeks (8 cases of simple metacarpal and phalangeal fractures and 5 cases of combined interphalangeal or metacarpophalangeal joint fractures), in 12 cases after 12 weeks (7 cases of simple metacarpal and phalangeal fractures and 5 cases of interphalangeal or metacarpophalangeal joint fractures), and in 3 cases of simple metacarpal and phalangeal fractures after 6 months. After removing the mini external fixation device and functional exercise, 3 cases of simple metacarpal and phalangeal comminuted fractures and 4 cases of combined interphalangeal or metacarpophalangeal joint fractures still had joint stiffness, but had no finger rotation and alignment deformity or chronic pain. According to the measurement of total active movement for 28 patients who obtained fracture healing, the results were excellent in 7 cases, good in 12 cases, fair in 5 cases, and poor in 4 cases, the excellent and good rate was 67.9%. Conclusion The mini external fixation device is a good technique for comminuted open fractures of metacarpal and phalange. In patients having comminuted open fractures with interphalangeal or metacarpophalangeal joint fracture, the results are fair or poor.