Taking the scheme adjustment of the rainwater system in a high-tech zone in Tianjin as an example, how to adjust the planning and design scheme of the areal rainwater system combined with the situation of current pipeline implementation after adjusting the rainwater design standard is discussed. By simulating the drainage condition with the mathematical model, the safety of drainage system is evaluated. And according to the sponge city construction requirement, the measures to improve the safety of drainage system are proposed.