Vibrational energy transmission through the bolt-nut system joining two elastic structures is important as it is one of the widely used fastening methods. In this work, the effects of fastening torque and washers are studied as major factors influencing the vibrational power transmission. An experimental method using the structural intensity technique is employed to investigate the characteristics of the power flow through the joint. It is found that the energy dissipation decreases with the increase of fastening torque until reaching the nominal one in the elastic range. Also, the test result reveals that increasing the number of washers is effective in attenuating the vibration energy transmission through the joint, but it is found that using more than 3 washers is not efficient in reducing the vibration transmission.