**4. Based on the Establishment and Simulation Analysis of Supply Chain Risk Propagation Model Considering the Recurrent SEAIR Model**

*4.1. Identification of the Causes and Results of Supply Chain Risks of Prefabricated Buildings*

From the perspective of system theory, the prefabricated building supply chain is a complex and huge system, and this paper analyses the risk factors affecting the prefabricated building supply chain from two aspects: the external system and the internal system. The stakeholders involved in the prefabricated construction supply chain include planners, purchasers, fabricators, transporters, and assemblers. This paper classifies these five stakeholders as internal systems that affect the risk propagation of the prefabricated building supply chain, and the external environment as external systems. System dynamics are used to analyse the influencing factors of external and internal systems in combination with Vensim PLE software, and identify the key factors affecting risk, that is, the main causes of risk.
