Powertrain mounting system (PMS) often operates with some degrees of uncertainty. These uncertainties may result from poorly known or variable parameters such as mount stiffness, or from uncertain inputs. For realistic predictions of the system behavior, the PMS models have to account for these uncertainties. To this end, the Chebyshev interval method is applied to study the uncertain characteristics of PMS.In the PMS, the location and orientation of each mount are off-design variables due to the space limitation of the powertrain. The stiffness coefficients of the mounts are considered as interval variables. The lower bounds and upper bounds of natural frequencies and the mode kinetic energy distributions of PMS are obtained using the Chebyshev interval analysis method. As a comparison, the scanning method is used to validate the interval method. The overall conclusion is that the Chebyshev interval method is a powerful approach for the simulation of PMS with interval parameters.