Bi1.5Zn1.0Nb1.5O7 (BZN) thin films with good surface morphology were prepared on fused quartz substrates by pulsed laser deposition (PLD). The X-ray diffraction (XRD) analysis and atomic force microscope (AFM) surface morphology measurements were performed on the samples. The XRD pattern demonstrated that the films are cubic pyrochlore structure and well crystallized. The AFM analysis indicated that the films have less rough surface. The fundamental optical constants, such as band gap, the wavelength dependence of the transmittance, and the refractive index, were obtained. The sign and magnitude of both real and imaginary parts of third-order nonlinear susceptibility χ(3) of the BZN thin films were determined by a single beam Z-scan technique performed at 1064 nm with a picoseconds laser. The third-order nonlinear refractive index coefficient γ and the nonlinear absorption coefficient β of the BZN thin films are 4.06 × 10−15 m2/W and −1.45 × 10−9 m/W, respectively. The real part and the imaginary part of the third-order nonlinear susceptibility χ(3) of the BZN thin films are 6.03 × 10−9 and 1.82 × 10−10 esu, respectively. The mechanisms of nonlinear refraction and nonlinear absorption were discussed. The results suggest that BZN thin film exhibit large third-order nonlinear optical properties and be a promising material for applications in nonlinear optical devices.