In smart-logistics ecological chains led by e-commerce platforms, the organisational efficiency has become an important indicator to measure the ecological chain's development. However, no scientific theoretical framework exists regarding the factors affecting such organisational efficiency. This paper adopts a multi-case study method to research four e-commerce platforms in China and investigate the current situation and development of smart-logistics ecological chains. Through interviews and analysis, the research proposes a theoretical framework of factors influencing the organisational efficiency about smart-logistics ecological chains led by an e-commerce platform. First, it reveals that under e-commerce platform leadership, the smart-logistics ecological chain's organisational efficiency directly relates to two factors: the eco-chain's technological innovation capability and contract fulfilment. Second, national policies, consumer demands, the competition among ecological chains, and Information-sharing will indirectly affect the smart-logistics ecological chain's organisational efficiency. Third, enhancing the smart-logistics ecological chain's technological innovation capability positively impacts its contract fulfilment.