It is noteworthy that 802.11 can be widely used in sensor networks for Power Substation. It providing data transmission between sensor nodes and data concentrator. The battery lifetime of nodes is essential for network system, Power management is an important technique to prolong the lifespan of sensor networks. Many Power-management protocols employ wake-up/sleep schedules, which are often complicated, inefficient and not suitable for applications in power substation. In this paper we propose a novel passive radio-triggered wake up circuit with an innovative power manager scheme to conserving energy in battery powered communication devices, which wake up standard 802.11 module only when needed and consume very low energy during the process of waking-up. Besides, it eliminate the extra energy that consumed by general wake up module. Comparing the result with always-on and rotation-based power management scheme for wireless network of power substation, we find our proposal saves more than 99.3% of the energy used in always-on scheme, and better than rotation-based theme which saves 66.7% of the energy. Thus the battery lifetime will be increased remarkably, specializes in wireless networks of power substation.