Aiming at the functions and requirements of the MAC protocols in Wireless Sensor Networks

this paper proposes an improved MAC protocol based on CDMA. According to the changes of network traffic

listen／sleep mechanism keeped most nodes in sleeping to save energy. And combined the technology of CDMA

the nodes used the high-speed pseudo-random code (PN) with the characteristics of uniqueness in network and orthogonality to modulate data signals

which can be overlapped in time and frequency

to achieve transmission in large-scale and real-time. Simulation results show that the protocol not only maintain lower system delay and higher through put

but also reduce energy consumption obviously.