<p>Integrated energy systems have been regarded as the crucial technical route for the energy system low-carbon transition to mitigate climate change. However, the integration of multi-energy systems is highly complex, introducing new risks and challenges to the secure operation of the system, especially in the current digital era. To address this issue, this paper proposed the multi-dimension risk diffusion assessment model to unveil the risk diffusion mechanism. First, this paper divided the heterogeneous risk systems into economic, social, natural, and digital risk subsystems. Second, the system dynamics model is adopted to simulate the heterogeneous risk diffusion. Third, the proposed risk diffusion model is verified with the integrated wind–solar–thermal-storage power generation park of China. The results show that the integration and adoption of digital technologies in integrated energy systems can significantly mitigate the output risks of renewable energy systems, such as wind and solar, caused by extreme weather events, thereby maintaining operational stability. This paper provides new insights into risk management in smart integrated energy systems, offering practical value for evaluating and controlling risks during integrated energy system planning and construction.</p>