Abstract: The wireless security system contains a host machine, which in turn contains a processing unit. The processing unit contains an evaluation module which in turn contains a data storage module. The host machine further contains an input/output device, a mode switch module, a wireless transceiver module, a configuration module and an alert module. The wireless security system further contains at least a sensor which in turn contains a wireless transceiver module capable of communicating wirelessly with the wireless transceiver module of the host machine The wireless security system achieves both the functions of home security and home care by having the mode switch module and the evaluation module. A user can set up the time intervals when the evaluation should function. Then, through the mode switch module, a user can switch between different operating modes, thereby avoiding false alarms and achieving the reduction of energy consumption.