Abstract: In order to effectively measure the security level of smart grid, to compare power network security during different stages in different or same regions, and to grasp the rhythm of power network development to realize the unity of quality, speed and efficiency, the security evaluation index system of smart grid is built from seven aspects, such as power access, structure security of transmission network, structure security of distribution network, efficient systems and equipment support, operation security and stability, adequacy and disaster resistant ability. By the thinking of combinational evaluation, the security of the smart grid is evaluated by AHP\|Entropy method, and the index and effectiveness of the method are verified by example. The results show that the security evaluation index system of smart grid can embody whole characteristics of development of power grid and security of power grid during construction of smart grid, which can be applied to inter\|regional evaluation and the same area evaluation at different stages.