How to use the established business ecosystem to effectively open the business model of the focus enterprise is an important issue in the theoretical and business circles. From the perspective of “availability” of business ecosystem， it matched niche roles and strategies of focus enterprises on the basis of identifying ecological functions/attributes， in order to explore the opening mechanism of new business model， and took Jingdong as an example to carry out grounded theory research. The results show that the focus enterprises in the center of the business ecosystem are usually faced with the rigid challenges of starting business models such as “lack of motivation”， “lack of ability” and “absence of subject”. Focus enterprises （eco-owners） should use the functional attributes of the ecosystem （exhibition venue， learning club， gravitational magnetic field） to position the roles of “vision presenter”， “knowledge coordinator” and “service leader” and match the “win-win”， “empowerment” and “attraction” strategies of the ecosystem. It aims to provide reference for the opening of new business model under the background of new economy， and also provide a theoretical basis for the business ecosystem and the process mechanism of starting business model.