Abstract: A uniform design experimental method was employed to discuss the interactive influence of Cl^- concentration, pH values and temperature on the pitting susceptibility of X120 pipeline steel in HCO₃^- + Cl^- solutions by a potentiodynamic scan technique. The experimental results indicate that Cl^-- concentration, pH values and temperature have great effect on the corrosion and passive behavior of X120 pipeline steel in HCO₃^- + Cl^- solutions, and the influence order is as follows:Cl^- concentration has the greatest impact, then the combined action of Cl^- concentration and temperature, the third one is pH values, and temperature has the smallest impact. X120 pipeline steel has the least pitting susceptibility in the HCO₃^- + Cl^- solution whose C1 concentration is 0 mol·L^-1, pH value is 8.5 and temperature is 0℃.