Abstract: Data aggregation is one of the most important approaches to alleviate the bottlenecks of resource in the Wireless Sensor Networks (WSNs). However, it is vulnerable to the attacks directing toward data confidentiality and integrity in an open and heterogeneous environment. To solve this problem, this paper proposes a Secure Data Aggregation (SDA) scheme based on the Homomorphic MAC for the WSNs, which is called SDA-HMAC. First, it adopts the Homomorphic MAC to check the aggregation data integrity; then it uses a homomorphic encryption scheme to ensure the data confidentiality; finally, it computes the hash function-based message authentication codes with time and key as the parameters to satisfy data freshness. The experimental simulation results and performance analyses denote that the SDA-HMAC can provide compared with other schemes, the data confidentiality, integrity, and freshness. It offers higher data transmission efficiency and more accurate data aggregation results while investing less volume of computation and communication.