This chapter deals with the robustness properties of serial manipulators with decoupled and coupled dynamics derived by tolerance analysis. After having introduced some performance indices of the manipulators, the tolerance capabilities of four manipulators are analyzed. In order to quantify the influencing degree, two kinds of the indices are defined. They are angular error and position error. Two kinds of simulation are designed here. The first kind of simulation is implemented by fixed parametric error. Then, the influencing degrees of all variables on the positioning accuracy of the manipulators are analyzed respectively. In order to obtain the models closer to the practical situation, the random parametric errors are introduced in the second kind of simulation. Furthermore, the parametric errors of all the variables are added at the same time during one simulation. The simulation results prove that the manipulators that decoupled by the mechatronic methods are more robust.