Photoaooustic effect of ZnO thin film was studied. Belations hip of photoaconstio signals and modulation frequency, incident light power, piezoelectric coefficient, dielectric constant, thermal conductivity and specific heat were deduced under one-dimensional condition. The experimental results were consistant with those from the theoretical analysis. Piezoelectric coefficient of ZnO film, 633=0.817 c/m2 and 631=-0.43 c/m2, were also calculated.