The purpose of this study was to investigate the effects of different rope-skipping exercise intensities on body fat. oxygen transfer system and refum - lipid in obese elementary students. Subjects were 21 obese boys in growth period and they were divided tinto two groups, 14 for and experimental group and the rest 7 for a controlled group. And experimental group was redivided into group A (7) and group B(7) They got 8 weeks different rope-skipping exercise intensity program. On the other hand, the latter group didn\'t get any exercises as susal. We measured their rate of %fat, changes of oxygen transter system and rerum lipid before and after the rope-skipping exercise. The variables of interrelation were analyzed and the results of this study were as follows. 1. The examined %fat of each group was significantly deceased after exercise. The experimental group A and B each were decresed to 14.8 %, 17.6% and there was significant difference in each groups. The controlled group was rather increased 0.7% after exercise. There is no significant difference. 2. We analyzed RBC, Hb, Hct, in blood to examine the change of oxygen trasnfer system in each groups and there was no significant defference with RBCm Hb, Hct. Besides no significant defference among group neither in disposal steps. But in case of Mgb, experimental A, B group show decreasing of 6.2% and no significant difference. 3. As for the density changes of total cholesterol, experimental A, B group show significant decreasing of 11.9% and 9.9% but the controlled group increased 3.9% . There was significant difference among groups(p<.05). 4. As for the changes of triglyceride, experimental A, B group show significant decreasing of 28.4%, 47.3% but the controlled group increased 8.4% . There was significant difference among groups(p<.01). 5. As for the changes of LDL-C, experimental A,B group show significant decreasing of 22.5%, 15.9% but controlled group rather increased 1.7% and no significant difference. These results suggest that 8 week-rope skippling exervise intensity program effect on increasing the rate of %fat, improving Mgb of Oxygen transfer system, decreasing TC, TG, LDL-C in serum lipid and significant increasing of HDL-c in obese elemenraty students. with above experiment we can certify that applying this program have good effect of decreasing of dangerous factor as obesity that applying this program have goold effect of decreasing of dangerous fator as obesity. Thus rope skipping as an aerobic exercise improves the chilhood physical function and it can help prevention and solution of an obesrity. So plenty of studies are demanded about exercise intensity and the development of various rope-skipping exercise programs are considered