In the era of mass leisure, homestay tourism has become a new driving force for balancing urban and rural development, invigorating the tourism economy, and helping rural revitalization and poverty alleviation. As a special type and manifestation of industrial agglomeration, homestay tourism agglomeration area is an important symbol to measure the development level of homestay tourism. But relevant academic attention is obviously insufficient. Based on the connotation of three elements of L-location, R-resource and Ddynamic, the paper constructs the L-R-D theory of the development of homestay tourism agglomeration. Taking the Yangtze River Delta, where homestay development plays a leading role in China, as a case, this paper mainly analyzes five development models of urban scenic market-oriented mode, suburban leisure market-oriented mode, historic village market-oriented mode, rural aging industry market-oriented mode and rural leisure market-oriented mode. It provides solid support and scientific reference for improving quality and increasing efficiency, and integrating and upgrading in homestay tourism agglomeration areas.