The organic carbon (C) of terrestrial ecosystems refers to the total organic C storage of a certain area of vegetation, soil, and litter. It is one of the important parameters for evaluating the C sequestration effect of terrestrial ecosystems. Accurate estimation of terrestrial ecosystem C storage and changes will not only help reveal the impact of global changes on terrestrial ecosystem C pools, but also help policy makers to develop climate response strategies and assess the effectiveness of the existing measures. Field observation data is one of the critical data sources for C storage estimation, however, only a few ecological stations have carried out the long-term observation. Most of the field observation data show characteristics of multiple-source, mismatch, and time discontinuities. Therefore, it is urgent to develop a scientific and standardized multi-data integration technology to reorganize these multi-source and scattered field observation data into a long-term systematically dynamic observation dataset, so as to increase the value of the data sources. In this paper, we systematically sorted out the observation status of some key parameters such as biomass and C content in different vegetation organs, soil organic C content, and bulk density in estimation of the vegetation and soil C storage. Additionally, we introduced scientific derivation methods of these key parameters and analyzed the method of multi-source field observation C storage data integration, which would provide reference for subsequently related research.