The aerial manipulator is a new kind of UAV system composed of an aerial robot and a multi-link manipulator. It enables the traditional aerial robots to perform fine manipulation, and thus has great potential for many real applications. However, one of the most challenging problems of the aerial manipulator system is the high performance steady control. Its difficulties mainly come from the heavy dynamics couplings between the aerial robot and the manipulator, especially when quick relative motion is required. Thus in this paper, the modeling and motion control problem of the aerial manipulator is studied. Firstly, a new modeling scheme is proposed by using the concept of Varying Inertial Parameters (VIP), the main idea of which is to take the influence of coupling on the aerial robot as a group of state dependent inertial parameters, i.e., the Center of Mass (CoM) and inertia matrix of the aerial robot is varying with the relative state variance. Subsequently, based on the VIP model, a feedforward compensation H∞ controller is designed to implement the steady flight of the whole system with relative movement. Finally, simulations are conducted and the feasibility and validity of the new proposed scheme is shown.