The article presents a new method of a structural analysis of the mechanisms in the mechatronic devices and robots, and formulas for analytical determination of the structural and constructive redundancy mechanism. The structural redundancy mechanism includes excessive contour connection, turning it into a statically indefinable system of extra contour and mobility (the ability of the link to rotate around its longitudinal axis or several links around their common axis, without affecting the functionality of the mechanism). The contour excessive communication can lead to an increased friction in the kinematic pairs or deformation of the links in the assembly, while the extra mobility contours lead to unnecessary design complexity of a mechanism. The constructive redundancy mechanism includes unnecessary links (the links, which do not affect its functionality, but influence the quality of its operation) and metric connections (the links, which duplicate the restrictions on the relative motion of the links in the mechanism). The excessive units increase the cost of a mechanism, while the metric connection can lead to blocking in case of inaccuracies in the manufacture of the links. The article presents examples of a structural analysis of the mechanisms and ways of elimination of the identified redundant links, the extra mobility and extra links, and metric connections. The proposed method of the structural analysis of mechanisms, robotic and mechatronic devices enables one to define a number of redundant and metric relationships, the extra mobility and extra links of each closed contour, and the degrees of freedom of a mechanism and its mobility. Application of this method allows us to design mechanisms without the structural redundancy, which facilitates the assembly process, reduces friction and wear in the kinematics pairs, and improves functioning of the mechanisms. This ensures high quality of the mechanical parts of the mechatronic and robotic devices.