Under action of normal pulse ruby laser radiation, electric properties of a piezoelectric ceramic thin plate of PZT system have been studied in our experiments. We have observed an unusual phenomenon before a small hole having been drilled by focusing laser radiation on the sample. When the laser radiation directs on it in either polarizing field (positive) or opposite direction (negative), we observe electric signals between two surface electrodes having same shapes and amplitudes, and their polarity is constant. As soon as a small hole has been drilled on the samples, in both sides above illumination cases, we observe eleotrio signals having jump changes in different ways, and one of them may be changed in polarity. This paper reports obtained experiraental results in our work, and makes a primary discussion to them.