International smart cities have been developed for decades. The United States，the United Kingdom，Singapore，Japan，South Korea，China，and other representative countries have a focus on the construction of smart cities through the relevant horizontal comparison. Trend analysis，each typical regional smart city development history，construction mode，involved areas，significant players，future development concerns，and the current development problems deserve attention. The international smart city construction presents five major trends such as e-government becoming the main support，further integration of infrastructure construction and smart technology，further increase of opportunities for public participation in smart city construction，the establishment of a more efficient comprehensive coordination mechanism，and big data becoming an important driving force for smart city development.