Abstract: Based on previous research on classification methods, this paper raises 6 principles that the classification system should obey. Drawing lessons from the comprehensive and sequential classification system of grassland (CSCS) proposed by Ren Ji-zhou et al, we suggest an integrated orderly classification system of natural wetland (IOCSNW) based on bioclimate- basement material- vegetation. The first level of the IOCSNW is class, and the classification indicators are depth of stagnant water and the years accumulated temperature above 0℃(∑θ) - these are quantified indicators. The second level is subclass, and the indicator is the basement material. The third level is type: emerging type, floating leaf type, submerged type, and floating type. According to bioclimatic and other indicators, the IOCSNW recognizes 21 wetland classes. The five largest areas of the wetlands classes are the frigid and shallow surface water wetland class (ⅠB), cool temperate and shallow surface water wetland class (ⅢB), cold temperate and shallow surface water wetland class (ⅡB), frigid and deep surface water wetland class (ⅠA) and warm temperate and shallow surface water wetland class (ⅣB). They occupy 79.75% of natural inland wetlands of China. These classes are distributed in the provinces of Qinghai, Tibet, Xinjiang, Gansu, Sichuan, Inner Mongolia, Jilin and Heilongjiang. While the warm and shallow surface water wetland class (ⅤB), tropical and shallow surface water wetland class (ⅦB), tropical and deep surface water wetland class (ⅦA), subtropical and shallow surface water wetland class (ⅥB), and cold temperate and deep surface water wetland class (ⅡA) are the smallest classes in area (they occupy only 0.83% of the total area) and are distributed in the provinces of Anhui, Hubei, Yunnan, Guangdong, Guangxi, Hainan, Guizhou and Qinghai. Twenty of the 21 classes occur in China since our data shows no wetlands of the tropical and seasonality surface water wetland class (ⅦC). Since the retrieval graph of the wetlands adequately embodies the genetic relationship of the natural inland wetlands, it lays the foundation to predict the succession of natural wetlands classes in a background of global warming and drying.