Review on estimation methods of forest carbon sink. Therefore, it is of great significance to estimate forest carbon storage and evaluate forest carbon sink function. The main methods are: 1. Biomass method. Through large-scale field investigation, the measured data were obtained, and a set of standard measurement parameters and biomass database was established. The average carbon density of vegetation is obtained from the sample data, and then the carbon density of each plant is multiplied by the area to estimate the carbon content of the ecosystem. 2. Volume method. Calculate the average volume (t/m3) of main forest tree species by sampling, calculate the biomass according to the total volume of forest, and then calculate the carbon fixation of forest according to the conversion coefficient between biomass and carbon. 3. Biomass investigation method based on the relationship between biomass and stock. Firstly, the carbon storage density (pc, mgc/hm2) of tree layer of each forest ecosystem type was calculated. Then, according to the ratio of tree layer biomass to total biomass, the total biomass carbon storage per unit area of each forest type is estimated to be 4. Eddy current correlation method. It is a micro-meteorological technology. This paper mainly measures the eddy current transmission rate of CO2 directly above the canopy, and thus calculates the fixed amount of CO2 absorbed by the forest ecosystem. 5. Relaxed vortex accumulation method. It is measured and calculated by three-dimensional sound velocity instrument and infrared CO2 analyzer. 6. Box method. Some plants are enclosed in a closed measuring room. The change of CO2 concentration with time is CO2 flux. 7. Determination methods of soil in forest ecosystem. Soil carbon density = soil volume × soil density× soil organic matter content ÷1.724; Soil reserve = soil subcategory area × average soil thickness × average soil bulk density × conversion coefficient. Excerpt from World Forestry Research, Volume 18, Volume 1 Carbon sequestration = output of carbon sequestration products × carbon content per unit product (energy) × carbon sequestration rate-