Pressure effects on the ionic transport and optoelectrical properties of lead halide perovskites are still largely terra incognita. Herein, we have conducted in situ alternating current (AC) impedance spectroscopy on both CsPbBr 3 powders and single crystals with random planes at pressures of up to 9.2 GPa and 6.8 GPa, respectively. Through the selection of different simulation equivalent circuit models of AC impedance spectroscopy, we have obtained the pressure-dependent electrical parameters of CsPbBr 3 . The current results indicate that all the CsPbBr 3 samples show mixed ionic-electronic conduction from ambient pressure to 2.3 GPa and pure electronic conduction at pressures above 2.3 GPa. We have also conducted in situ photocurrent measurements on CsPbBr 3 powders at pressures up to 2.9 GPa. The emergence of extremely sharp and needle-like peaks at every moment of light irradiation at pressures below 2.3 GPa is attributed to the mixed conduction within CsPbBr 3 , and the photocurrent of CsPbBr 3 could hardly be detected at pressures above 2.9 GPa. Additionally, the photoelectric response of CsPbBr 3 can be enhanced by compression, and the strongest photocurrent value appears in the high-pressure phase at 1.4 GPa.