Urban green spaces occupy a large share of urban ecological land and directly serve as carbon sinks in the urban ecosystem. They are also an important means to achieve the dual carbon goals. However, current research on urban green spaces mainly focuses on carbon sinks, while few studies address carbon emissions accounting, and the calculation process is complex. This article uses greening projects as an example to detail the process of accounting for carbon emissions using the basic unit method. The various stages of greening projects are divided into diff erent basic units, with emission factors as important parameters. Using the standard consumption quota and the corresponding emission factors for consumed resources, a carbon emissions accounting method for the entire life cycle of greening projects, based on basic units, is constructed. A database is established from basic unit data to enable quick querying of corresponding units and matching of their carbon emission data, thereby effi ciently calculating the total carbon emissions of greening projects. Compared with traditional carbon emission accounting methods, the open design and data iteration update mechanism of the basic unit method increase the accuracy and practicality of carbon emission accounting; it also solves the current problem that carbon emission accounting for greening projects lacks a modular subdivision unit. This method will provide a replicable and scalable technical solution for carbon emissions accounting in urban and rural construction and contribute professional expertise to achieving the dual carbon goals in the landscape and greening industry.