In many engineering applications, the fusion motion involving many components is required, each motion component has different properties. The different motion properties can be roughly divided into two types according to frequency and amplitude, namely, low frequency high amplitude and high frequency low amplitude, however, the commonly used driving device often works in only one mode. For this kind of application demand，a 6-[(RPRRRP)R-R]US parallel mechanism was designed to realize dual-mode motion fusion. The novel mechanism evolved from the typical 6-RUS configuration. The method of transforming the original driving pair R into (RPRRP)R-R dual-input sub closed loop mechanism was discussed. The forward and inverse kinematics solutions of the novel mechanism under single montion component mode and two components fusion mode were analyzed respectively. Two kinds of strategies, which was for allocation of dual-input inverse solution, were proposed. The forward kinematics of the novel mechanism was divided into two steps: firstly, according to the characteristics of dual-input sub closed loop, dichotomy method was used;secondly, for the outer 6-RUS configuration, forward kinematics was conducted by means of Newton method. Flow charts of the two steps were given. Through numerical examples, theoretical calculations were carried out for the inverse solution of dual-mode fusion under uniaxial motion, inverse solution of dual-mode fusion under multi-axial composite motion and for the forward solution driven by dual-input fusion, meanwhile, the kinematics simulation of numerical examples in different cases was carried out. The results showed that the difference between the theoretical value and the simulation value was on the order of 10-6, the correctness and validity of the theoretical method were proved. The mechanism proposed can be used as the pointing and stability coordinate adjustment device of vehicle-borne, shipborne and space-borne equipment to improve the operation performance.