<p>Risk assessment of cascade dam systems is an important process for identifying potential safety hazards, supporting engineering designs and contributing to the stable operation of the system. In response to the challenges associated with quantifying the risk transmission effect and the inherent complexity of systematic risk evaluation, this paper adopts a causality-based approach to systematically analyze and explore the mechanisms underlying risk transmission. On the basis of clarifying the failure definition in cascade dam systems, a calculation model for the failure risk rate and failure loss of the system considering the risk transfer effect was developed. By combining probability and loss, the risk measurement of the cascade dam system has been achieved. In addition, the risk level classification standard was refined, which offers a scientific basis for risk assessment of cascade dam systems. Finally, using nine dams on the Golmud River as an example, the feasibility and potential applicability of the proposed model and method were illustrated. This method takes into account the transmission effect of individual dam risks, shows promising computational efficiency and reasonable accuracy, and may facilitate the quantitative evaluation of risks within cascade dam systems, thereby offering a useful reference for the regulation of such systems.</p>