Geosynthetic reinforced soil retaining walls have been used successfully as earth retaining structures for more than five decades. The main reasons for their popularity are reduction in cost, ease of construction and better performance. In geotechnical engineering it is very important to study the interaction behavior between soil and geosynthetic in reinforced earth applications. At the first part of this study, the pull-out tests were carried out in order to determine the interaction parameters. Moreover, attempts such as coating of polyvinyl acetate and polypropylene fibers on geotextile have been made to increase these parameters. As expected, by use of polyvinyl acetate, the stiffness per unit area and soil-interface friction angle were increased 14/4% and 19/1%, respectively. Consequently it was attempted to determine the effective length of geotextile in pull-out tests by numerical approach. Based on these results, the 0/5L length of the geotextile can be reported as the effective length. In the second part of this study, it was attempted to investigate the influence of reinforced parameters including reinforced length and vertical space between reinforcements by experimental and numerical approaches. Results obtained from this investigation showed the optimum bearing capacity and performance of the reinforcing length at 0/7H and vertical space between reinforcements = 10cm for a wall with 60cm height. At the last part of this study, the performance of two full-scale soil reinforced retaining walls has been investigated using FLAC3D program. In this section, the effect of reinforced length and interaction parameters on horizontal displacements and failure modes have been investigated and safety factors of walls have been obtained in several cases. The results of horizontal displacements showed the optimum reinforcement length which were found at 0/7H. Moreover, the maximum horizontal displacements of the wall 1 and 2 were decreased 7/9% and 16/2%, respectively when the interaction parameters were increased 20%. Keywords oil reinforced retaining wall, interaction parameters, pull-out test, reinforced length, numerical analysi