The ionic electrical conduction in sintered Bi2O3-Y2O3 system for samples containing 20-30 mol% Y2O3 was investigated by means of measurement of ac conductivity and the emf of oxygen gas concentration cell using the specimen tablet as electrolyte. The experimental po2 range from 1 to 10-21 atm for ionic electrical conduction measurement-These materials showed high oxygen ionic conduction, the conductivities for samples containing 22.5-30mol% Y2O3 are many times higher than those of stabilized zirconia ZrO based solid electrolyte at corresponding temperatures. When these materials are used to construct an oxygen concentration cell, the E/E0 is equal to 1 or approaches 1. These values show that the samples containing 22.5 to 30 mol% Y2O3 are nearly pure ionic conductors. The p-type hole conductivity is very small at higher po2 values, so it is negligible. The n-type electronic conduction was investigated by means of coulomb titration technique for Y2O3 27.5 mol% sample We obtained that lg pe＇=-767000/T +665. The pe＇ is equal to 2.6×10-61 atm at 800℃. The n-type electronic conduction is vary small, so that it is also negligible.These materials are proved to be good high ionic conductors.