Weight reduction and strengthening of the body is the major factor in automobile industries. It improves the fuel efficiency and safety factor of the vehicle. Inner engine cover is an important component of heavy vehicles. It is mounted inside the vehicle cabin. It reduces noise transfer from the engine and protects the engine from debris, dust etc. In this paper, we have focused on the effect of the stiffener and weight reduction of engine cover by optimizing design. The suitable material used for engine cover for low weight and low thermal conductivity is SMC polymer. This paper presents the static stress analysis, modal analysis and harmonic analysis of Engine Cover to identify the effect of stiffener and composite material on vibration response of engine cover. It is observed that the static deflection and vibration response amplitude of SMC polymer material Engine Cover is less as compared to other counterpart materials. This paper investigates the effect of stiffener on vibration response of engine cover using ANSYS Software.