By building a game model between brands and outsourced anchors, this article systematically studies the incentive design, opportunistic behavior and blockchain governance mechanism in live streaming. We found that while promoting the sales efforts of anchors, commission incentives will also induce opportunistic behaviors such as AI rhetoric exaggeration, traffic manipulation and channel encroachment. Secondly, blockchain technology can effectively suppress opportunism by improving the traceability of information and the verifiability of behavior: on the one hand, it increases the marginal cost of implicit violations, On the other hand, contractible punishment is imposed on explicit sexual encroachment. The key threshold conditions in the study show that when the sum of the incentive intensity and the blockchain punishment exceeds the encroachment of personal interests, the encroachment can be completely suppressed. The study further reveals the three-state equilibrium model of the optimal blockchain governance intensity: strong governance, weak governance and precise governance. Its choice depends on the trade-off of product characteristics, incentive costs and governance benefits. At the same time, the governance effect is affected by the power structure of the platform, and the platform, as a provider of governance infrastructure, may have the problem of insufficient motivation. Based on this, this article proposes that the sustainable development of live ecology requires building a comprehensive system of incentive contracts, technical governance and institutional environment coordination. It also provides a theoretical framework for understanding the problem of entrusted agencies in digital marketing and a decision-making basis for the governance practice of the platform economy.