As a new carbon-negative emission reduction technology, CO2 capture utilization and storage (CCUS/CCS) has attracted more public attention. Environmental safety is the key to the succeed of CCUS/CCS projects, and environmental monitoring is an important means to verify and evaluate the effectiveness and safety of the project. Based on the identification of project risk scenarios and harmful factors, combined with relevant research and the exploration of CCUS demonstration project, this paper constructs a set of environmental monitoring technology system including aboveground space, surface and underground location, involving the monitoring objects such as atmosphere, soil, wellbore casing head, surface water, shallow groundwater and produced gas (liquid), and proposes monitoring indicators, monitoring methods and evaluation thresholds. On the basis of the construction of the monitoring system, the practice and application of the monitoring technology system taking the ultra-low permeability sand conglomerate CCUS demonstration project in the Junggar Basin as an example were carried out, and the monitoring and evaluation results showed that various indexes were below the threshold limit, and the operation of the CO2 geological utilization and storage project was safe and reliable. The establishment of an environmental monitoring system for CO2 geological utilization and storage projects can provide reference value for the CCUS industrial application and the development of other projects, and promote the green development of the CCUS/CCS industry chain.