This paper examines the critical pathways for traditional industries to achieve cross-border integration in the context of the digital economy, grounded in the profound reshaping of traditional industrial ecosystems by platform economies. The study first analyzes the survival crises and transformation opportunities faced by traditional industries under platform economies, then introduces niche theory to establish a three-dimensional analytical framework of “platform-industry-user.” Through empirical case analysis, the paper identifies core issues in cross-border integration, including niche gaps, resource misallocation, and competitive barriers. It proposes platform-enabled niche-building strategies, encompassing technological coupling, organizational restructuring, and value co-creation, aiming to provide theoretical support and practical guidance for traditional industries in seeking new spaces for survival and development amid the platform economy wave.