The ionic conductances of polycrystalline Rb4Cu16I7Cl13 for both porous and dense specimens have been measured between - 80-8°C under hydrostatic pressure from 0.5 to 11.6 kbar. A conductance maximum exists near 4-5 kbar on conductance versus pressure curve for porous specimens, while the conductance decreases with pressure for dense specimen. The temperature dependence of conductance under constant high pressure is the same as that under atmospheric pressure. The pressure does not obviously influence the a →β phase transition temperature. The activation volumes are 0.90 cm3/mol and 1.55 cm3/mol for α and β phase respectively.