In this paper, the performance of a Kenics and SMX static mixer combination is investigated with regard to the specialty of tertiary oil recovery. The experiment has the same scale with industrial process as the diameter of test static mixers are 50 mm and the effective length are 1500 mm. The experiment mainly focuses on degradation of polyacrylamide solutions of different concentrations and different relative molecular mass, the pressure drop of the static mixer combination and mixing performance of polyacrylamide solutions through the static mixer combination. The experimental results show that the degradation rate of polyacrylamide solutions and non-uniformity degree are positively related to polyacrylamide solution concentrations, relative molecular mass of polyacrylamide and liquid phase flow rate. With more solvent distributed among the macromolecular chain entanglements, the flow resistance of macromolecules is reduced, which leads to the reduction of the viscosity of HPAM solution. This phenomenon mainly accounts for the degradation of polyacrylamide solutions. In this study, the pressure drop of the static mixer combination and non-uniformity degree of product solution have obvious advantages compared with other static mixers used in the same way. The results show that the static mixer combination is very suitable for mixing process of polymer solution and water from oilfield. (C) 2014 Elsevier B.V. All rights reserved.