During spraying, vibrations of sprayer booms, which take place because of unevenness of soil and tractor velocity, affect the success of spraying. When vibrations increase, this situation cause disruption of spraying pattern and leaf coverage. Thus, the yield of agricultural product drops. Manufacturers desire durable field sprayer boom during the spraying operation. To do this, they manufacture various suspension systems to damp vibrations. Beside vibration, weight of the field sprayer boom is very important. Most manufacturers start to use aluminum due to its lightness and corrosion resistance reasons. In this study, for the same field sprayer boom design, materials of mild steel and aluminum are compared via modal analysis with finite element analysis in a CAD Program. According to results of modal analysis field sprayer boom which made of mild steel has 7.4 Hz natural frequency under its own weight that applied from own center of gravity. And also same field sprayer boom which made of aluminum has 8.15 Hz natural frequency under its own weight from own center of gravity. The costs, weights, and manufacturability of materials are also compared.