Abstract: The information delays introduced by the complicated control communication chain make uncertain risks on the system dynamics. Meanwhile, the converter dynamics are affected by the interacted terminals. Therefore, it'sit is necessary to build the multi-terminal system model considering the control delay and the communication delay in the system to investigate the delay effect on the system dynamics and stability. To address this concern, the delay components inside the MMC-HVDC system arewere dissected and the multi-terminal dynamics arewere derived. On the basis of the harmonic modeling, the multi-terminal MMC-HVDC system with multiple delays was modeled. Moreover, a unified Pade approximation form for multiple delays was proposed to quantitatively analyze the model stability. Various physical scenarios were tested to validate the model accuracy. With the proposed model and the unified multi-delay analysis framework, the delay stability region was drawn and analyzed. The complete stability chain was detected and the results show that the tight coupling of the internal dynamics enhances the spread of cyber-delay effect, which causes the stability region distortion. For multi-terminal MMC-HVDC, the interaction between the physical system and the cyber system should be considered sufficiently whenduring programming and designing.