4 kinds of crosslinked polyacrylamide water retaining agent from Beijing Hanlimiao New Technology Limited Company was used as the experimental material to study. The water absorption, water release and macronutrient absorption performance of different specifications of water retaining agent in different concentrationsolution was studied to do the screening test of water retention agent. Fertilizer and water conservation screened out the best performance of water retaining agent, added to the nursery, tomato...