Harvest agricultural products are perishable. If they cannot be sold, there will be serious grain loss and food waste. It is an important issue related to human sustainable development and urgent to address. As the most popular way of shopping, live shopping has achieved remarkable achievements, while the existing research is relatively silent on how to promote the sales of agricultural products in the context of live streams. Based on S-O-R theory and dual-system theory, three studies investigated the intrinsic mechanism of consumers' impulse purchase intention in live streams. The results show that scarcity promotion and cause-related events are positively correlated with consumers' impulse purchase intention. The intrinsic mechanism is respectively arousal and moral elevation. Interestingly, when scarcity promotion and cause-related events are presented at the same time, the impact of cause-related events on impulse purchase is no longer significant. Overall, the proposed model could be used to predict consumers’ willingness and provide the choice of marketing strategy to promote the sale of agricultural products, which has significant theoretical and practical value.