To consider dynamic load while equivalent standard axle load conversion is carried out,two degree of freedom vehicle model is built to calculate power spectral density of dynamic load coefficient,and then distribution of dynamic load coefficient is calculated.Increasing degree of equivalent standard axles is calculated in theory while dynamic load is considered.The results of examples show that equivalent standard axle load shall be increased when dynamic load is considered for various kind of pavement: for asphalt pavement,while design deflection and tensile stress at the bottom of asphalt pavement is taken as index,1%-2% shall be increased for expressway and first class highway,2%-5% shall be increased for other classes highway;while tensile stress at the bottom of semi-rigid base is taken as checking index,3%-6% shall be increased for expressway and first class highway,7%-17% shall be increased for other classes highway;for cement concrete pavements,15%-25% shall be increased for expressway and first class highway,35%-80% shall be increased for other classes highway.