Abstract: The parameters of rocks under ultrahigh-pressure state are very important to problems of geodynamics and explosion engineering. In these experiments, plane wave dynamite lenses were used to drive the flying plates. The flying plate hits the target and produces an ultrahigh-pressure shock wave. The propagation velocity and the particle velocity of shock wave in rock samples ware measured by probes, and the relation between density of rocks and pressure was obtained by the Rankine-Hugonito formula. Samples of limestone and granite were studied. The maximum pressure attained in experiments was highet than 70 GPa. The ultrahigh-pressure state formulas obtained are: Limestone: p = 3.22 + 0.016 p; Granite: p = 3.20+ 0.024 p; where the unit for p is g/cm3, the unit for p is GPa.