To eliminate the hysteresis phenomenon between the photodeformation and the photovoltage of PLZT(Lead Lanthanum Zirconate Titanate) under the irradiation of high energy light,a novel photostrictive constitutive equation in multi-energy fields was established and the influence factors of the hysteresis phenomenon were investigated by experiments.Firstly,the light-thermal-electric-elastic coupling mechanisms of the photostrictive effect under a lighting were analyzed theoretically and the constitutive relationship of photostrictive effect was established.After that,a novel constitutive equation was obtained by the derivation of anomalous photovoltaic effect,thermal effect,pyroelectric effect,thermal expansion effect and piezoelectric effect.Finally,the photostrictive constitutive equation was validated through the temperature screening test and photostrictive static experiments.Experimental results indicate that the temperature rise of PLZT ceramic is the main reason of hysteresis phenomenon;and the variation trends of experiment curves are agreed well with the theoretical results,which confirms the reasonability of the theoretical model.Moreover,the photodeformation of the PLZT in the experiment takes about 10 s to reach saturation after eliminating the temperature rise.It shows that reducing the temperature rise effectively eliminates the hysteresis phenomenon and improves the response speed of photodeformation.The novel constitutive equation provides a theoretical basis for driving and controlling of PLZT ceramics.