Intelligent Transportation System (ITS) has become one of the important policies of major countries in the world. ITS is being developed for nearly 30 years, with emerging technologies and software and hardware upgrades, the technology integration has become the main development item. Different transportation needs lead to different development priorities and projects among different countries. However the main goal keeps consistent, namely to improve the safety, efficiency and sustainability of the transportation systems. This article introduces the policy and development of ITS in major countries in the world.