Lead lanthanum zirconate titanate, PLZT ceramics have drawn great attention in microactuation because the Photostrictive Effect in it. In this study, compositional dependence of photostrictive effect in PLZT was investigated. The factual compositions were configurated quantitatively by XRF to characterize the deviation in the preparation process. Different sintering periods were designed in an attempt to obtain PLZT ceramics with the same grain size but different compositions to explore the intrinsic photostrictive effect in the PLZT system. With this method, the maximum intrinsic photocurrent was obtained at 3.48/50.7/49.3, while the maximum intrinsic photovoltage was obtained at 3.44/52.73/47.27.