Urban green space is an important ecological space for direct carbon sequestration and indirect emission reduction in cities, but its construction and operation and maintenance process will also produce carbon emissions. Accounting and evaluating the carbon sequestration and emission of urban green space throughout its life cycle, and adopting sink increase and emission reduction measures according to local conditions are an important basis for consolidating and improving the carbon sequestration capacity of urban green space. This paper reviews the carbon source/sink accounting methods of urban green space. The carbon emission accounting methods mainly include footprint method, attribute method, filling method, etc., calculation method based on international standards and guidelines, mathematical model based on research, field observation and laboratory measurement, etc., among which the greenhouse gas inventory accounting method is the most widely used. Carbon sink accounting methods mainly include field measurement method, assimilation method, micrometeorology method, remote sensing estimation method and information technology measurement method. The methods of afforestation increase mainly include optimizing local seedlings, selecting low-carbon landscape materials, moderately transforming terrain, and using modern information technology for efficient management and control. To summarize the accounting methods and the technology of increasing sinks and reducing emissions, in order to provide a scientific basis for the development of related research and the application of methods and technologies; To provide scientific support for the improvement of urban green space carbon sink capacity and the realization of urban carbon neutrality.