During the past 200 years, approximately one-half of the carbon dioxide from human activities is being taken up by the oceans. The uptake of carbon dioxide has led to a reduction of the pH value of surface seawater of 0.1 units, equivalent to a 30% increase in the concentration of hydrogen ions. If global emission of carbon dioxide from human activities continues to rise at the current rates, the average pH value of the oceans could fall by 0.5 units by the year 2100. This was equivalent to a three fold increase in the concentration of hydrogen ions. Global ocean acidification has become one of the most threatening disasters to the ocean ecosystem and has been attached great importance by the countries adjacent to oceans and the related international organizations in the world. In this paper the current situation and development of ocean acidification and the impacts of ocean acidification are described. It also summarizes the latest research achievements of ocean acidification and the ocean acidification studies in such countries as US, Europe, Japan, Australia, the Republic of Korea, and China, etc.