Surfactant flooding is one of the common tertiary method to recover remaining oil in the reservoir, by reducing the interfacial tension (IFT) between two immiscible fluids nevertheless, current surfactant forms emulsion and difficult to achieve ultra-low IFT between the water and oil without addition of co-surfactant. In this research, two types of anionic lignosulphonate-based surfactants, Sodium Lignosulphonate (SLS) and Calcium Lignosulphonate (CLS) are chosen as co-surfactant. The main surfactant used in this project is the common anionic surfactant, Sodium Dodecyl Sulfate (SDS) at a fixed concentration of 4 mmol/l. Each type of co-surfactant with different concentrations (0.5, 1.0, 1.5 and 2.0 wt ) was mixed with 4 mmol/L of SDS at each test tube to create the surfactant solution. The result of the experiment showed that at 0.5 wt for SLS and CLS surfactant solution, the contact angle of oil to surface lowered down with a reduction of 6° and 7° respectively. This indicate that the system will be more water-wet which the oil droplet will be less adhesive to the rock surface. In conclusion, by using the optimum concentration of 0.5 wt lignosulphonate as co-surfactant is able to alter the wettability of rocks and it is recommended to test the biological-based co-surfactant at increasing temperature as an alternative to enhance the surfactant flooding performance which improves the oil recovery. © 2020 Chinese Petroleum Society