As one of the most important systems in mechanical engineering, almost all the multibody dynamic mechanical systems (or mechanisms) involve various uncertain factors, which may influence the performance of a system especially for the high-speed dynamic systems. For instance, the geometry size of a component in the mechanism has a tolerance to facilitate manufacturing process; the fabrication of different kinds of raw material may lead to the inhomogeneous distribution of the material, which will further lead to the variation of material properties, such as the Young's modulus, Poisson's ratio, and material density. To improve the computational accuracy of dynamic analysis of the mechanism, it is necessary to investigate their dynamic responses by considering these unavoidable uncertain factors. The dynamic study of the mechanisms under deterministic conditions has been developed from traditional rigid multibody systems to flexible multibody systems and rigid-flexible multibody systems. The modelling of rigid multibody systems has been well studied [1], and some commercial software has also been widely used. On the other hand, the study of flexible multibody systems and rigid-flexible multibody systems has been attracting more and more attention over the past two decades. When the flexible components are involved in multibody systems, the deformation of these flexible components has to be considered. Since flexible components in multibody systems often experience large rotation and deformation, the traditional finite element methods based on the small rotation and deformation may give an improper solution [2]. However, the Absolute Nodal Coordinate Formulation (ANCF) [3] shows good capability for solving flexible multibody problems with large rotation and deformation. ANCF defines elemental coordinates as the absolute displacements and global slopes, which forces the mass matrix of the system equations to remain constant and the centrifugal and Coriolis forces identically equal to zero [4,5]. As a non-incremental finite Uncertain dynamic analysis for rigid-flexible mechanisms with random geometry and material properties Jinglai Wu a, ⁎