In recent years, public security becomes more and more important. In this paper, we design a hardware platform to use a 24GHz band radar module to detect multiple objects. We propose a signal processing method that can segment multiple objects in a signal sequence, and a data processing method that can identify different materials, including metal, water, and petrol. Experiment results show that our proposed method can divide multiple objects with 100% accuracy and identify each object's material with 91% accuracy. The platform can be easily deployed widely to make a ubiquitous security surveillance system benefits from radar's cheap cost and small size.