Currently wireless sensor network is one of the most hot research in Network of Things. How to control energy consumption to prolong the network survival time in wireless sensor network becomes one of the most concerned problems. In order to achieve effective control of energy consumption, an energy saving mechanism was established based on multi channel wireless sensor network by building energy consumption model. It based on CSMA protocol, and in order to control energy consumption it controls back-off process in non-persistent CSMA protocol and physical layer modulation. And combined with the characteristics of multi channel wireless sensor network, it used multiple channels, so the energy saving mechanism added the available channel number. At last the simulation result proved that it could improve energy efficiency.