The charge transport behavior of barium fluoride nanocrystals is investigated by in situ impedance measurement up to 35 GPa.It is found that the parameters change discontinuously at about 6.9 GPa,corresponding to the phase transition of BaF2 nanocrystals under high pressure.The charge carriers in BaF2 nanocrystals include both F-ions and electrons.Pressure makes the electronic transport more difficult.The defects at grains dominate the electronic transport process.Pressure could make the charge-discharge processes in the Fm3m phase more difficult.