Hydraulic engine mounts are used to support powertrain and reducing transmitted vibration from motors to the frame. Hydraulic engine mounts are elastomeric mounts with fluid traveling between the top and the bottom rubber chambers. A fluid channel between the two rubber chambers, called ‘‘inertia track’’, is used to connect them together. The resonance caused by the travelling fluid in the inertia track can create a tuned vibration absorber effect to provide vibration isolation at a particular frequency called notch frequency. One important use of hydraulic engine mounts is in the air industry. In turbofans, the maximum amplitude of vibration occurs at the two distinct frequencies. So, by using an engine mount with maximum flexibility at these frequencies, one can achieved reducing thetransmissioof theengineinducedvibratioto the cabin. Linear modeling of this mount is done by researchers. As nonlinear terms are neglected in previous studies, here, the modeling is carried out by considering these terms. Here in this thesis, using bond graph method, linear modeling of a double-notch hydraulic engine mount is done. Then, by applying nonlinear terms, nonlinear modeling of the engine mount is carried out using variance method. It has been shown that the dynamic stiffness will be changed by considering nonlinear terms. Sensitivity analysis is applied to show the effect of each parameter on the dynamic behavior of the mount. The variation of each hydraulic engine mount parameter on the location of the notch and peak frequencies and dynamic stiffness at these frequencies is studied. In this analysis, each parameter of the mount is varied by 20% and the percent change on the location of the notch and peak and dynamic stiffness is recorded. It has been shown that the diameters of first and second inertia tracks are most effective parameters on the second and first notch frequencies, respectively. By using sensitivity analysis results and based on an initial geometric model, drawings and engine mounting formation in modeling 3-dimensional (3D) is created using CATIA software. Then, by applying finite element software, main rubber stiffness, its volumetric stiffness and the equivalent cross section of the upper chamber is calculated. Middle rubber volumetric stiffness is obtained with the same method. Fluid inertia and the damping in the inertia track are calculated using theoretical relations. Using these parameters, dynamic stiffness of hydraulic engine mount is simulated using MATLAB. Then the final model is fabricated and some test experiments is done. Obtained dynamic stiffness from test is compared with the simulations and acceptable agreement is observed. Keywords: Vibration isolation, Hydraulic engine mount, Nonlinear modeling, Dynamic stiffness, Notch frequency