Through selecting the representative countries and analyzing their top-level technology roadmap of smart grid, it can be instructive to find smart grid development trend and research the key points and thinking in smart grid development. This paper picks up the technology roadmap in America, European Union and Japan as the research objective. Based on the illustration of the contents of the roadmaps, the universalities and differences among them are summarized. What is more, the reasons are discussed in terms of energy resources, economic society development, power grid situation and so on. The results show that the future smart grid has common traits. The first is the renewable energy is emphasized in generation side. The second is wide area interconnection is preferred in power grid structure, and the security, reliability and efficiency of network is highlighted. The third is the interaction between power companies and consumers should be highly improved. Meanwhile, since the differences of socioeconomic condition, power network situation, energy distribution and so on, the emphasis points in technology roadmaps in different countries are not same. The diversity shows as the focuses on renewable energy types firstly. Secondly, the methods of security, stability and efficiency improvement of power network are various. Thirdly, the ways of pushing intelligent power consumption are not same. The results in this paper are valuable for smart grid development and technology route optimization.