Abstract: To address the autonomous take-off and landing problem of a compound unmanned aerial vehicle (UAV) on the confined platform of a high-speed unmanned surface vehicle (USV) under complex sea conditions, an autonomous take-off and landing decision-making and guidance method is proposed for UAV-USV cooperative systems. The method constructs response-window safety criteria based on rotor thrust build-up, normal separation dynamics, and short-term platform attitude prediction to temporally align effective action establishment with a relatively stable interval of platform motion, and employs a phased relative guidance and tracking strategy across fixed-wing and rotary-wing modes to accomplish return rendezvous, deceleration, close-range following, and landing. In flight tests conducted on a vehicle-mounted swaying platform, the platform travelled at an average speed of approximately 38.5 km/h, with average pitch and roll angle ranges of ±10.5° and ±16.5°, respectively; the UAV completed safe take-off and autonomous landing, and the mean lateral and longitudinal errors over three landing tests were approximately 0.05 m and 0.04 m, respectively. The proposed method coordinates take-off and landing timing determination with phased relative guidance, thereby enabling stable autonomous take-off and landing of the compound UAV under high-speed motion, significant attitude disturbances, and confined take-off and landing space.