The product space of the world in four periods(1992-1994, 1999-2001, 2004-2006 and 2009-2011) were developed basing on the exporting data from UN Comtrade database. The product space of the world have a core-periphery property in common,with more sophisticated products such as mechanics,instruments and chemicals in the core,and other labor-or resource-intensive products dispersed outside. The developed countries have the revealed advantages mainly in the core products,while developing countries in the periphery ones. Comparing the positions of different countries in the product space of different periods,it is found that the emerging industrialized countries such as the Four East Asian Dragons have realized continous evolutions of their revealed comparative advantages from periphery products to the central ones,while some countries with unsuccessful economic performances have experienced long stagnation in such progresses. <<