With the global environmental problems becoming increasingly serious, how to protect the environment while ensuring economic development has become a common global challenge. Circular economy as a new economic development model, with its unique way to deal with this challenge. This paper will discuss the concept and operation of circular economy, as well as its challenges and opportunities in the field of environmental protection. First, the concept and operation mode of circular economy circular economy is a kind of economic development mode which aims at realizing resource circular utilization, reducing environmental pollution and improving economic benefit. Its core is to organize economic activities into a feedback process of“Resources-products-renewable resources” through technological innovation and institutional innovation, make rational and sustainable use of matter and energy in this process. Challenges of the circular economy 1. Technical difficulties: the realization of circular economy needs the technical support of high efficiency and environmental protection, but at present some technologies are not mature or high cost, which limits the promotion of circular economy. 2. System deficiency: circular economy needs perfect laws, regulations and policy support, but the system construction of some countries and regions is still not perfect. 3. Public Awareness: despite the importance of circular economy to environmental protection, part of the public is not aware of it, lack of participation and support.

Opportunities in the circular economy 1. Economic Development: Circular economy helps to improve the efficiency of resource utilization, reduce production costs, promote the development of green industry and inject new impetus into economic growth. 2. Environmental Protection: A Circular economy helps improve environmental quality and maintain balance of nature by reducing emissions and resource consumption. 3. Social well-being: a circular economy helps raise public awareness of environmental protection, create green jobs and enhance social well-being. Conclusion: as a new challenge and opportunity in the field of environmental protection, circular economy is of great strategic significance. In the face of technical problems, institutional deficiencies and public awareness, we need to increase technological research and development, improve laws and regulations, improve public awareness, and promote the healthy development of circular economy. At the same time, circular economy also provides unlimited opportunities for economic development, environmental protection and social welfare. We should seize these opportunities and work together for a green and sustainable future.