In large-scale online promotion activities (OPAs), how to stimulate, obtain and monopolize consumers’ platform trust has been a key prerequisite for e-commerce platforms to stand out in the increasingly fierce and homogeneous market competition. We selected the Alibaba Double eleven shopping Carnival and Jingdong 6.18 shopping Carnival as the empirical cases and conduct fsQCA analysis on 613 valid questionnaires. The research shows that there are four configurations that affect consumer platform trust. Three of these configurations are composed of self-efficacy, expected relationship benefits, perceived festival atmosphere and perceived snap-up atmosphere. Activity satisfaction plays a significant role in triggering consumer platform trust. In addition, the results confirm the critical role of positioning intensity. The finding of the research has practical significance for network marketing planners and online shopping platform operators.