This study focused on soil behavior behind a flexible retaining wall. A strip footing was placed at three distances of 1B, 2B and 3B (B= Footing width) from wall and loaded. Randomly fiber reinforced soil with Dr=40% was tested. The soil underneath the footing has placed at four conditions of unreinforced, 1B, 2B and 3B depth of reinforcing. High quality pictures were taken during tests and analyzed by PIV method for observation soil movement. Results showed while footing was at distance of 1B, reinforcement had not any considerable effect on improving ultimate bearing capacity of soil (UBC). At this condition, strength of wall had more effect on soil behavior and its resistance. When footing placed at distance of 2B, reinforcing of soil caused shear failure surfaces moved deeper and this leaded to improvement on UBC. At this distance increasing reinforcement depth increased UBC. When distance of strip footing increased to 3B, soil acted independently from wall and failure surface did not reach to wall.