This paper introduces the evolving features of China-Southeast Asian economic relations since the beginning of the 21st century from the aspects of bilateral trade, cross-investment, and other forms of economic cooperation, and explores the driving forces of accelerating the economic relations of both sides from the different perspectives of global, regional and country level. It analyzes the problems that exist and predicts the opportunities and challenges brought forth to the Southeast Asian countries by China’s economic adjustment and large-scale industrial restructuring and rejuvenation programme under the context of global economic recession. Keywords: China and Southeast Asia, economic relations, evolving features and challenges. This paper is divided into four sections. Section 1 is the introduction of the whole paper. Section 2 introduces the evolving features of China-Southeast Asian economic relations since the beginning of the 21st century from the aspects of bilateral trade, cross-investment, and other forms of economic cooperation such as trade in service, financial cooperation, tourist cooperation as well as China’s aid and assistance to the new ASEAN member countries. Section 3 explores the driving forces of accelerating the economic relations of both sides from the different perspectives of global, regional and country level. Section 4 further analyzes the problems that exist and predicts the opportunities and challenges brought forth to the Southeast Asian countries by China’s economic adjustment and a large-scale industrial restructuring and rejuvenation programme under the context of global economic recession.