Under the background of the express-reconstruction of the Qinghai-Tibet Highway being proposed, it will be necessary to employ the special technique of cooling the ground temperature by the crushed rock embankment in order to protect from damage to highway embankment due to thaw settlement. Under vibrating load, the porosity variation of crushed rock layer may weaken the cooling effect of buoyancy-driven natural convection of the pore air in the crushed rock layer of the highway embankment, thus resulting in instability and failure of the road embankment structure. Under these conditions, the effect of vibrating load on the porosity of the crushed rock layer must be studied both theorectically and experimentally. In this work, laboratory experiment on the porosity variation of the crushed rock layer under vertically vibrating loads is developed based on the water flooding approach and the experimental method is introduced. The test results indicate that due to the vibrating load the crushed rock layer causes the compacting effect and the shapes of crushed rock grain tend to be non- angular.