In order to reduce the water cost of polymer flooding, it is necessary to find a stable, easy to treat and cheap alternative water source. In this experiment, natural lakes in Daqing area were taken as the target water source. Based on the water quality monitoring of relevant lakes, the differences of the polymerization effect between lake water and clean water and the possible influencing factors were understood through the comparison of the results of polymerization stability, shear resistance and scanning electron microscopy. Corresponding simulated polymerization experiments were designed for Ca2+, Mg2+, Na+ and bacteria to explore the influence of each factor on the viscosity of polymer solution under the condition of mass concentration in lake water, and the lake water treatment technology was discussed according to the experimental results, to achieve the goal of preparing polymer solutions by treated lake water. The results show that the three-step filtration process of “quartz sand + fiber bundle filter material + ion exchange resin” can make the water quality of the treated lake water reach the same level as that of clean water, and the corresponding experiment results also verify that the polymer solution preparation effect of the treated water from the process is comparable to that of clean water.