The invention relates to a path planning based flexible spacecraft attitude adaptive control method. First softening operation on an expected angle of a spacecraft is performed based on an SMPPa attitude maneuvering path planning method; on-line parameter identification is performed by utilizing a gradient descent method based on a flexible spacecraft mathematical model based on the feature modeltheory, and a three-axis model feature parameter is determined; a control moment is determined according to the determined flexible spacecraft mathematical model and the feature parameter thereof, theflexible spacecraft attitude is controlled through the control moment, and finally the steps are repeated until the angle reaches the expected spacecraft angle. According to the path planning based flexible spacecraft attitude adaptive control method, the influence of flexible accessory vibration on control performances is restrained, attitude control steady accuracy and dynamic characteristics are improved, and the path planning based flexible spacecraft attitude adaptive control method is suitable for the flexible spacecraft having three-axis coupling nonlinear characteristics.