The structures and growth kinetics of the complex surface films on copper in sodium chloride solutions (pH = 9) containing low concentrations of benzotriazole have been studied by X-ray photo-electron spectroscopy and a BAW sensor. It is shown that there are some differences in growth kinetics and structures for these surface complex films, even though the copper surfaces prior to the contact with BTA are of the same state and the treated solutions have a same pH value (pH = 9). When the BTA concentration (C-BTA) in the treating solution is zero, low (< 0.17 mM) and high (greater than or equal to 0.17 mM), the film growth can be best represented by a linear, parabolic and logarithmic law, respectively; and the corresponding structures of the surface films of copper are the multilayer structure of Cu/Cu-Cu2O, Cu/Cu-Cu2O/CuO-Cu(I)BTA and Cu/Cu-Cu2O-Cu(I)BTA, respectively. With C-BTA increasing, the growth kinetics of the surface film changes from a parabolic law to a logarithmic law, the critical concentration of BTA is 0.17 mM, above which CuO cannot be detected in the surface film and a higher inhibition efficiency can be obtained.