In-network data aggregation in wireless sensor network has been shown to improve scalability, prolong sensor network lifetimes and diminish computational demands. However, the node that plays the role of data aggregation will consume much more energy than common nodes and may quit the mission in advance due to energy exhausting because of taxing decryption and re-encryption operation; moreover, it will bring complex key management to ensure the security of the data and corresponding keys. This paper was designed specifically to address above problem based on the thought of privacy homomorphism. It can achieve the perfect security level equal to one-time pad with much lower energy consumption; moreover, it can be proved to resist the attack of node capture. Using the simulation and analysis, we show that our scheme consume the energy only about 21% of AED scheme. However, the node that plays the role of data aggregation will consume much more than common nodes and may quit the mission in. advance due to energy exhausting because of taxing decryption and re-encryption operation; moreover, it will bring complex key management to ensure the security of the data and corresponding keys. This paper was designed specifically to address above problem based on the thought of privacy homomorphism It can achieve the perfect security level equal to one-time pad with much lower energy consumption; moreover, it can be proved to resist the attack of node capture. Using the simulation and analysis, we show that our scheme consume the energy only about 21% of AED scheme.