A finite-time control scheme is presented to address the attitude tracking problem of over-actuated spacecraft, in which reaction wheel misalignment, external disturbance and uncertain mass of moment inertia are considered. A finite timecontroller using adaptive sliding mode control technique is developed. It can guarantee finite-time reachability of the given attitude motion even in the presence of external disturbances, and uncertainties in the configuration matrix due to reaction wheel misalignment and mass of moment inertia. Numerical simulation results of an application to spacecraft show the effectiveness of the proposed attitude tracking control law.