The unknown dynamics of failed spacecraft constitute a formidable technical challenge for attitude takeover control. Therefore, an attitude takeover control method is proposed for failed spacecraft with unknown parameter. Firstly, a modified adaptive dynamic inverse control is proposed to reconstitute the control law of service spacecraft, and the Lyapunov method is used to analyze the stability of the system. Then, the reconfiguration of thruster is implemented, which is to reconstitute the configuration matrix of thruster, and not to change the physical configuration of thruster. Furthermore, the thrust forces of thrusters can be redistributed by the control reallocation based on null-space pseudo-inverse, and achieve the attitude takeover control for failed spacecrafts with unknown parameter. Finally, numerical simulations validate the feasibility of the proposed method.