This article presents results of our studies on PZT-8 polycrystalline ferroelectric ceramics of lead zirconate titanate. We have measured the dielectric constant and dielectric loss over a low frequency range (from . 100kHz-20MHz) and temperature range from room temperature to 500℃. The mechanism of dielectric loss, the relaxation process and the impurity effects are discussed. The main loss above Tc is attributed to conducting loss.We also propose some suggestions for improving electrical properties of PZT-8 ferroelectric ceramics.