Sprinkling management is indispensable for lawn-planting in greening urban areas. In this study, numerical experiments are performed using 1-D soil-plant-atmosphere continuum model in order to quantify the effect of sprinkling on the temperature distribution in four types of lawn covered soil. Obtained simulation results are investigated from the viewpoints of sprinkling efficiency, storage capacity of rainwater, and reduction effect of sensitive heat. They are summarized as follows, 1) Suitable sprinkling plan should be chosen according to the soil hydraulic properties and the drainage condition. 2) Optimum sprinkling level can be estimated based on the maximum effective soil moisture and the sprinkling control condition. 3) Maintenance of high heat conductivity of the surface soil by controlling soil moisture proved to be effective for the improvement of heat environment.