The work aims to improve the barrier properties of biaxially oriented nylon film and study the effect of stretching on film properties. Kaolin clay and nylon-6 (PA-6) were selected as raw materials to prepare the biaxially oriented PA-6/kaolin blend barrier films by melt blending and biaxially oriented technology. Tensile strength tester, oxygen transmission tester, X-ray diffraction analyzer (XRD) and Fourier transform infrared spectrometer (FT-IR) were used to characterize and analyze the properties of the films, respectively. When the mass fraction of kaolin clay was 2.0%, the tensile strength of the films in machine direction (MD) and transverse direction (TD) increased by 4.9% and 6.5%, and the elongation at break also increased by 6.0% and 4.2%, respectively. When the mass fraction of kaolin clay was 4.0%, the barrier properties of the films increased by 16.51%. The elasticity modulus, tensile strength and barrier properties of the films increased as the stretch ratio increased, while the elongation at break decreased. The results of XRD and FT-IR showed that stretching promoted the transformation of γ polymorphs into α polymorphs which had a more stable structure. Thus, the addition of kaolin clay can improve the mechanical properties and barrier properties of the films. Also, the discussion of different stretching conditions can provide reference for further study on the stretching mechanism, properties and process conditions of the films.