Abstract: In order to ascertain the effect of water-retaining agent on the characteristics and distribution of soil pore in different soil layers, the technique of CT (Computed Tomography) scan was used to study characteristics of soil porosity under potted experiment when Triticum aestivum L. harvesting. The results indicated that soil pore number, porosity and pore round rate increased after application of water-retaining agent, which promoted transmission of soil moisture and nutrition. With the increase of applied water-retaining agent, average total pore number, total porosity and into round rate in different soil layers increased, but over a certain amount of applied water-retaining agent the total number of pore increased not obviously, while total porosity and pore round rate decreased, but still higher than the control (CK). The order of biomass and yield of wheat applied with water-retaining agent was as follows: 54mg/kg>81mg/kg>27mg/kg>CK. It was concluded that water retaining-agent improved characteristics of soil pore, promoted the growth of Triticum aestivum L. and increased yield. In addition, among different treatments the effect of treatment by appling 54mg/kg of water-retaining agent on the biomass and yield was the highest, and compared to control, the biomass and yield increased by 13.1% and 22.2% respectively.