WE used polyethylene oxide (molecular weight =5×106), with addition of diffcrent weight of ＣｕＢｒ2 (ratio n=[EO]/[Cu]= 4，8，12，16,24), to prepare a series of high polymer ionic conductor （ＰＥＯ）n－ＣｕＢｒ2. Their complex impedance spectra in the high hydrostatic pressure range of 0.1-350 MPa and alternating conductivity in the pressure range of 0.1-2400MPa were measured. Results show that pressure dependence of conductivity can be decomposed into four saperimposed linear dependences components. According to phase analysis of X-ray diffraction curve, these straight lines respectively belong to pressure effect of amorphous phase of PEO，pressure effect of crystalline phase of PEO and pressure effect of new phase CuBr2. Hence the relation between compositiod n and activation volume, limit pressure of the three types of conductivity-pressure effect were calculated. Finally we found that by adding a small amount of plasticizers, C4H6O3, can increase elasticity of high polymer film （ＰＥＯ）n－ＣｕＢｒ2 and enhance its ionic conductivity under high pressure one or two order of magnitude.