[Purpose/Significance] The purpose is to explore the predetermined behavior of resource demanders based on the information generated from the perspective of multi-layer trust on the shared service platform, so as to facilitate the recovery and sustainable development of the sharing economy in the post-pandemic era.[Method/Process] Combined with the trust information of the supply and demand sides on the platform, between the supply and demand sides and the demand side on the shared products, based on the "3P+3I" theory from the perspective of multi-layer trust, a research model of consumer purchasing behavior of the shared service platform is constructed. Taking the shared short-term rental platform as an example, this paper obtained the public data of Airbnb in Beijing area, used Bert algorithm to construct the reputation index of housing products, and preliminary speculated the internal mechanism of user reservation behavior based on causal discovery algorithm in causal inference, and used Poisson regression to conduct empirical analysis.[Result/Conclusion] The trust variables of both parties to the platform, between the two parties and the demander to the shared product had a significant positive promoting effect on housing sales. The trust characteristics generate by hosts had the largest positive effect on tenants' booking behavior. It is suggested that hosts should make great efforts to establish the reputation of hosts and disclose more information appropriately. In order to obtain the badge of "super host", they can give priority to not providing "direct booking" service so as to screen out users who may have malicious comments. It is suggested that platforms strictly check the personal qualifications of users. More attention should be paid to improve the identity information authentication mechanism and comment incentive system for users, so as to reduce the uncertainty in users' decision-making.