The smart distribution grid exchanges information relying on communications network increasingly, and the communication network becomes more diverse and open, which makes the communication packet vulnerable to be attacked by malicious third party such as information falsifying, forging, stealing. On the basis of researching packet security objectives of smart distribution network, this paper presents a packet authentication algorithm based on elliptic curve for smart distribution network communication. First the principle of digital signatures is discussed. Then the specific implementation of smart distribution network packet security based on digital signatures is introduced, and the packet security test is carried on the current intelligent distribution network platform. The experiment results show this packet authentication algorithm based on elliptic curve has better security and also can meet the real-time requirements of smart distribution network communication.