Although IEC62351 suggests no encryption algorithm for GOOSE and other real-time packets due to the huge time consumption of encryption algorithms,many practical power projects still encrypt GOOSE packets to strengthen the security of network information.In this paper,the classical Rijndael symmetric encryption algorithm is adopted as an example to analyze such factors affecting the time consumption of GOOSE packets encryption as the secret key length,the packet length and the packet mode.Then,in order to reduce the time consumption without weakening the packet confidentiality,a GOOSE encryption method based on critical information is proposed with the combination of packet domain implication.Moreover,GOOSE messages such as StNum,SqNum and T,which possess time synchronization functions，are used to prevent replay attacks,and the CRC verification code in GOOSE packets is used to ensure the integrity of the message.Finally,the time-consuming characteristics of the proposed GOOSE encryption and decryption algorithms are tested on an embedded platform,and the results show that the proposed method meets the real-time requirements of power systems well.