In the context of electronic countermeasures, addressing the issues of acceleration saturation and unreliable communication links during multi-vehicle cooperative guidance, an adaptive high-reliability cooperative guidance law with relative impact velocity and impact angle constraints is proposed. First, an online target acceleration estimator based on a nonlinear disturbance observer (NDO) is constructed to improve robustness against maneuvering targets and uncertain disturbances. On this basis, a state-dependent adaptive term is introduced into the traditional double power reaching law to effectively mitigate the impact of acceleration saturation on guidance stability. Second, addressing the scenario of communication link interruptions, a fixed-time open-loop cooperative strike fault-tolerant backup guidance law is designed, along with a smooth switching strategy for control variables, thereby enhancing the reliability of the overall guidance process. Simulation results under various conditions, including ideal scenarios and communication interruptions, demonstrate that the proposed cooperative guidance law can achieve cooperative attacks on maneuvering targets with the desired relative impact kinetic energy and impact angles. The adaptive term effectively attenuates overload saturation and enhances guidance stability, while the system can rapidly switch to the fault-tolerant scheme to ensure mission completion even under communication interruption. Monte Carlo simulations further verify the adaptability and robustness of the proposed method under parameter perturbations and uncertain initial conditions.