The paper presented a lightweight high-level encryption algorithm for Wireless Sensor Network, referred to as the IAES. The algorithm conducted a variety of improvements form AES, mainly in three areas. At first, fewer algorithm rounds from 10 to 7; secondly, the polynomial coefficients transformation in MixColumn operations; finally, utilization of polynomial generator of the finite field designs and implements a look-up table methods to improve the speed multiplication of polynomial. In the experimental validation stage, we analysis the proposed improved algorithm with the AES algorithm from the RAM and ROM storage space overhead, CPU clock cycles, network latency in CC2430 wireless node platform. The experimental results show that the improved algorithm in the node RAM and ROM storage space overhead have a small increase, its CPU clock cycles and network latency are superior to AES algorithm.