Inland water is an important component of the global carbon （C） cycle and plays a key role in regulating climate change. The Primary Productivity （PP） of inland water is defined as the amount of organic matter produced by primary producers in inland water bodies through photosynthesis per unit time and unit area， which reflects the quantitative relationship between the organic and inorganic C pools. The assessment of inland water PP can help analyze the C cycle mechanism of photosynthesis and quantify the C absorption of aquatic ecosystems to examine the differences in the ecological environment in different regions and evaluate the importance of inland water bodies in the global ecosystem C cycle. There are many methods for estimating PP in inland water， including the light-dark bottle incubation method， the vertically generalized production model method， and the ¹³C method. Each of these have application scopes and limitations. The unreasonable use of PP restricts the understanding of its variability and driving mechanism in inland water bodies. The mechanism， advantages， disadvantages， and applicability of each method are compared by summarizing domestic and international research on PP estimation methods in recent years. Two new methods based on dissolved oxygen concentration or oxygen isotopes， namely， diel O₂ technology and ^18/16O technology， are introduced. This study serves as a reference for research on inland water metabolism， productivity， and nutrient cycles.