Oriented to the needs of marine resources development and safety monitoring, to further enhance the accuracy of state estimation for offshore platforms, considering the observation and attitude systematic errors of the airborne observation platform, the optimal observation configuration for the airborne observation platform, cooperative offshore platform, and offshore platform is investigated. The air-sea cooperative error reduction method is employed to reduce systematic error and estimate the target state for the offshore platform. The target state estimation error caused by systematic errors is calculated based on first-order Taylor expansion. The optimal observation configuration under various systematic errors is derived, including range, azimuth, elevation, yaw, pitch, and roll systematic errors, and the multi-platform optimal observation configuration under the combination of systematic errors. The comprehensive analysis of these errors leads to the conclusion that the optimal observation configuration among the platforms is achieved when they are aligned in a straight line, with the airborne observation platform gradually approaching the target. Simulation experiments in typical scenarios verify the correctness of the theoretical derivations.