Chemical flooding is a promising method of enhanced oil recovery through improving the oil displacement efficiency. The surfactants can effectively reduce the interfacial tension (IFT) between the injection fluid and the residual oil. Petroleum oxidation soap (POS) as a surfactant has the potential for use in chemical flooding owing to its easily gained, cheap and favorable behavior. This study was an attempt to investigate the interfacial activity of POS as well as the adsorption characteristic on oil sand. The experimental results provided a practical instrument for the application of POS in chemical flooding and a method for broadening its application.