In a typical integrated power system （IPS），the generator sets，transmission lines and distribution network are integrated in a relatively confined space，which leads to the tight coupling between the devices and accelerates the propagation of cascading failures.A risk assessment model of cascading failures in unmanned platform IPS is established based on pattern search theory and risk assessment theory，which is used to analyze the cascading failure of IPS under severe operating environment and frequent mode switching.Based on the model，a risk assessment is performed on a typical MVDC IPS，and the influences of different operation conditions and reliability parameters on the cascading failure risk are also analyzed.The proposed risk assessment model is validated through risk assessment and anlysis.Based on the risk assessment results，the weak links of the system are identified，and the corresponding prevention strategies are proposed by optimizing the equipment structure.The proposed cascading failure prevention strategies are verified through both simulation and experiment.