With the integration of 3G Network and Wireless Sensor Network, the Internet of Things is considered to be one of the most important technologies of the new century. For the Internet of Things, how to extend the working time of sensor nodes is the core problem. At present, there are two specifications of power management: APM (Advanced Power Management) and ACPI (Advanced Configuration and Power Interface) which are designed for PC. Due to their complexity and the requirements for BIOS layer, these two methods are not applicable to wireless sensor node. In this paper, the signalslot framework was developed firstly. Secondly, based on signal-slot framework, a simple and effective power management scheme-SPM (simple power management) was designed and applied in the popular sensor node operating system Contiki.