The explosion of liquid carbon dioxide tanks are extremely rare in the world, this article describes the 125 m3 liquid carbon dioxide tank explosion that happened on a ship. This paper gives a comprehensive analysis and calculation on the explosion energy and hazard radius as well as the causes of the accident, with the explosion energy being converted to TNT equivalents. Tank explosion radiuses leading to death, serious injury and different degrees of destructions are also obtained via theoretic calculation. According to the calculation, this article points out that the direct cause of explosion is that the designer confuses the concept of " Low-temperature vessels" with the concept of " Low-temperature and Low-vessels Low Stress vessels". The reasons of the tank explosion accident are not only the mistaken design but also the operating violation. Finally the article also makes a reflection from four different perspectives.