The total porosity of the high performance concrete under cyclic loading was measured in this present paper. Results show that finite cycles of cyclic axial tensile load causes permanent damage to concrete, which can be measured after unloading. The higher the applied upper load level or the more the cycle number is, the more obvious will be the connection and development of micro cracks. Then the higher will be the total porosity. Especially, with the increase of cyclic load number, the total porosity of the concrete shows obvious stage characteristics. And there is a linear relationship between the total porosity and cyclic loading cycles in the second developing stage of fatigue strain.