Abstarct: Low Back pain is one of the common symptoms in adults and due to its high prevalence in adolescents with chronic association with older age is of interest to everyone. Evidence shows that this rate is higher in competitive level athletes than the non-athletic same age population. To prevent back pain in adulthood it should be recognized risk factors in youth. baxsed on the evidence the relationship between the strength of trunk and the back muscles has widely been investigated But this relationship between adolescent soccer plaxyers has been less investigated. The present study is a cross – comparative study that the aim of this study is to find the common causes of Low back pain in adolescent Fotball plaxyers. For this purpose, baxsed on a LBP questionnaire 30 children and young footballers were selected and divided in two groups with and without low back pain. After that, various factors such as age, height, weight, training hours per week, age of start of competitive sports, the difference between the two lower limbs, the hamstring muscles tightness , back muscles and lower back endurance, the rate of flexibility of the back muscles and waist, the diameter of the abdominal wall muscles and multi Fydos muscles measured. Then relationship between these factors and low back pain and VAS scores were studied with some of the above factors. To evaluate the differences in scores between the two groups of various statistical tests were performed at a significance level of less than 0/05. The results showed that the difference in mean age, height, weight, training hours per week, age of competitive sport and endurance of back muscles and lower back, hamstring muscles tightness, the symmetry and stability of the ankle and the back muscles and lower back flexibility, diameter of MF and EO muscles and back pain in children and young footballers, there was not a significant relationship. But the difference of diameters of Oblique Int and TrA muscles and back pain between the two groups is significant. Therefore, with the mention of the relationships of above factors with the back it is recommended to the coaches of children and adolescent in beside of technical and tactical training, use the fitness programs to strengthen the abdominal muscles and back for prevention of back pain