Using robotic arms to capture space debris is a promising method in active debris removal. Since most space debris is uncooperative target, uncertainties exist in the inertial parameters of the combined spacecraft after target capture. In this paper, an attitude takeover control method based on adaptive dynamic programming is investigated for the postcapture combined spacecraft. The controller requires no inertial information. Firstly, the dynamic and kinematic model of combined spacecraft is established. Then, the learning-based control, action-dependent heuristic dynamic programming with actor-critic structure is introduced. Finally, the algorithm is tested with the benchmark cart-pole system and the combined spacecraft. Simulation results show that the inertia-free control method is sensitive to the learning parameters and initial weight of the actor and the critic, which will bring problems in practical use.