Abstract: In order to promote the reasonable application of self-made composite water retaining agent on protected substrate cultivation for water-saving, difference of the properties of water absorption and retention and germination percentage between composite water retaining agent and the control (MP3005 KM) were compared in this paper. With β-cyclodextrin, sodium carboxymethyl cellulose, soluble starch, bamboo charcoal powder and pyrolytic corncob as raw materials, composite water retaining agents were prepared by using water bath heating. pH values, swelling degrees, water absorption rates, dehydrating rates, frequent absorbency and germination tests were analyzed and compared with analysis of variance (ANOVA) and multiple comparison tests. The results showed that four kinds of self-made composite water retaining agents all had better properties on the water absorption and retention than the control which the optimal composite water retaining agent was the β-cyclodextrin + sodium carboxymenthyl cellulose + soluble starch + pyrolytic corncob. The β-cyclodextrin + sodium carboxymenthyl cellulose + soluble starch + pyrolytic corncob had higher swelling degree (183.98 mL/g), higher water absorption rate, lower water dehydrating rate and its germination index (GI) was nearly 7 times higher than the control. The study can provide a theoretical reference for development, production and application of water retaining agent in China.