Shock loading-release is performed on the porous aluminum with micropore and porosity m=1.04. Time-resolved interfacial velocity between the porous aluminum and LiF window is measured with diatance interferometer system for any reflector (DISAR) under five pressures ranging from 53 GPa to 99 GPa . From the interfacial velocity, the Euler longitudinal sound velocities under five pressures and the bulk sound velocities under 53 GPa, 72 GPa and 91 GPa are obtained. The melting pressure of the material is about 81 GPa. The poisson ratio before shock melting is about 0.37. From the analysis, the existence of the micropore in the material reduces the the shock melting obviously. So, its induced anharmonic effect cannot be neglected. Considering anharmonic effect into the equation of state, the anharmonic parameter is calculated to be about 30.