Abstract: In this paper, the life cycle assessment method (LCA) was used to analyze the carbon footprint of the whole cycle of Undaria pinnatifida aquaculture and processing industry. The types and extent of carbon emission sources in each link were identified. The results showed that the total carbon emission in 100 mu cultivation of U. pinnatifida and processing was 3.95×10⁵ kg CO₂ e, which was much higher than carbon sequestration from 100 mu cultivation of U. pinnatifida. The results showed that the U. pinnatifida industry was not a carbon sink industry based on the analysis of the whole industry. The carbon emissions in the processing stage were the largest, followed by the storage stage. The emission sources in the processing stage were mainly from heavy use of paper shell, while those in the storage stage mainly were from the electricity consumption of refrigeration equipment. In the cultivation stage, the consumption of diesel is the main factor affecting carbon emissions. Therefore, it is suggested to reduce the carbon emissions of U. pinnatifida industry and enhance the carbon sink capacity of U. pinnatifida industry by changing energy forms, improving the service life of materials and selecting low-carbon alternatives.