The purpose of this research is to study how the stretching exercise along with heat and electric therapy can effect on Angle of Lumbar Flexion and Reduction of Pain against the Hamstring Construction Symptom that can be found in the Chronic Low Back Patients. The target of research was 28 person selected out of the patients diagnosed as Lumbar Sprain and Lumbar Syndrome, who have positive from the active test of Hamstring construction and passive test. Their age range is 20 to 60 years old, 14 male and 14 female. As a research method, simple heat and electric therapy was applied to counter part while Hamstring Stretching Exercise including simple heat and electric therapy was applied to the experimental part. After 6 weeks treatment for each part, the results of effect on Angle of Lumbar Flexion and Pain Reduction was compared and analysed on the basis of the gravity angle meter and Visual Analogue Scale (VAS). The outcome of research is as follows: 1. Angle of Lumbar Flextion increased effectively not in the conventional counter group but the experimental group to which Hamstring Stretching was applied simultaneously. 2. remarkable effect was shown in the experimental part applied Hamstring Stretching. Consequently from the results of this study, we could find out the fact that the therapy combined preserve treatment and hamstring stretching not only produced increasing Lumbar Flexion Angle but also was more effective on reducing pain of the patients according to it than the conventional or preserve therapy.