Peatlands are globally important organic carbon pools, and play a key role in the global carbon cycle and climate change. Based on the existing estimates of peatland area and peat reserves in the world and in the continents, combining with the data of organic carbon content, carbon storage in peatland in the world, in the continents and in some main countries was estimated. The results showed that organic carbon storage in peatlands was about 238.134 billion metric tons of carbon in the world. The organic carbon unevenly distributes in peatlands of the continents. The organic carbon storage in peatlands in North America was about 109.864 billion metric tons of carbon, accounting for 46.14% of the total carbon storage in the world, which was the most abundant. The organic carbon storages in Europe and Asia were accounting for 27.41% and 22.89% of the total, respectively. At present, many countries still had not accurate data of peat reserves and organic carbon storage in peatlands. The main obstacle of estimating organic carbon storage in peatlands lied in the different definitions of peatlands among countries, lacking data base of peat thickness and peat bulk density, or due to the different scope of statistics, leading to inaccurate estimation. Finally, main influencing factors of dynamic of organic carbon storage in peatlands were presented. The results of this study tried to provide scientific basis for the sustainable use of peat resources and protection of carbon storage function of peatlands.