This paper designs an energy-saving floor drain to collect the heat of wastewater. It has a good heat transfer performance which was proved by mathematical models and experimental data. The models include the heat exchanger model of spiral flow and the heat exchanger model of serpentine tube. The model of spiral flow shows the process of exchanging heat between the water in the energy-saving floor drain and its wall. The model of serpentine tube shows the process of exchanging heat between the wall of floor drain and wastewater. Besides, an experiment is introduced to verify its ability of absorbing heat. The experiment responses the energy-saving capabilities of floor drain. Finally, its performance of energy-saving and emission reduction ware analyzed with experimental data and statistical data.