The application of chemical amendments is an important way to improve soil and water availability of farmland. It is the basis for rational use of chemical methods to improve soil by understanding the effects of chemical amendments on soil water movement processes. In this study, the effects of different chemical amendments on soil infiltration and evaporation characteristics were studied by applying different rates of polyacrylamide (PAM) and sodium carboxymethyl cellulose (CMC). The results showed that with the increasing rates of chemical amendments applied, both amendments hindered soil water infiltration and inhibited soil surface evaporation. Considering the performance of water retention and evaporation inhibition for different amendments, the effect of applying CMC was higher than that of PAM, and the CMC application rate of 0.08% was the best. Under the same effect on water retention and evaporation inhibition, the application rate of CMC was less than that of PAM, and thus CMC had a wider application prospect. This study could provide a theoretical reference for rational use of chemical amendments for soil water retention and evaporation inhibition.