Supracondylar fracture of the humerus is the most common elbow injury in children and adolescents, and it also has many considerable complications. Especially, cubitus varus deformity out of the complications is very unsatisfactory result to the patient in recovery periods in functional and cosmetic viewpoints. Not only nearly or perfect anatomic reduction but aiso accurate measurement of varying angle at the fracture site were necessary to minimize this potential problems. Therefore, the author measured the angles of 250 patients elbow X-ray using Trochlea-Capitellum angle method, a new method of radiological assessment for comparison to carrying angle & Baumanns angle methods. And it appears that this method has statistically less error risk and to be easy to measure angle on X-ray films. Next, the author reports the excellent results of K-wire percutaneous fixation treatment compare to open reduction and internal fixation with statistical siginficance. From the authors retrospective clinical & radiological study of 250 supracondylar fractures, the following results were obtained. 1. Mean differences of the angle between the normal & injured arm were 7.25 in carrying angle, 5.07 in Baumanns angle, and 3.97 in Trochlear-Capitellum angle. 2. K-wire percutaneous fixation group patients stayed in the hospital only average 3.3 days, shorter than average 8.9 days open reduction and internal fixation group. 3. T-test of T-C angles between the K-wire percutaneous fixation and open reduction & internal fixation group show no significant difference. Therefore the former treatment is recommandable. 4. According to the Flynns evaluation, the results of K-wire percutaneous fixation treatment were Excellent in 87 cases(69.1%), Good in 28 cases(22.2%), and Fair in 11 cases(8.7%).