A power monitoring system comprises an input module, a plurality of switches, a plurality of power supply ports, a detecting module, a control module, and a wireless transmission module. The each switch was set in between the input module, and each switch has an address. The detecting module generates a power loading value by set in between the input module and each power supply port. The control module connects to switches, the detecting module and the wireless transmission module, thus, the control module can read the power loading values from the detecting module, and control each switch which corresponds to the address by a preset rule or a command from the wireless transmission module. It will not only save energy but also improve the electricity security for the household.