This work investigates the performance and inter-sectoral interaction mechanism of China's largest vertically integrated care network, the national medical alliance (NMA). The data collected derive from the China Health Statistics Bulletin and the China Health Statistical Yearbook for the period 2009-2018. The data include 64 observation indicators for five medical sectors in the NMA, namely, tertiary hospitals (THS), secondary hospitals (SHS), community health centres (CHCS), township hospitals (TsHS) and professional public health institutions (PPHIS). This research combines complex systems theory with a multilevel structural dynamic factor model, and yields two main results. First, although the trend for the NMA's global factor is increasing, the evolutionary paths for sectoral factors differ substantially. Among the sectoral factors, the sectoral factor of THS continued to decline, and neither the sectoral factor of CHCS nor the sectoral factor of TsHS has significantly improved. Then, the interaction mechanism between the various NMA sectors is investigated. While a close relationship has been formed between THS and CHCS and between SHS and CHCS, there remains no close two-way relationship between either THS and TsHS or THS and SHS. Thus, going forward, to reach the policy expectations, China's NMA implementation must consider the interaction between different constituent sectors.