With increasing growth of technology in the today’s world it seems necessary to produce goods having high-quality and low cost. During some applications textile materials expose to the sunlight or UV radiation. It seems essential to study and investigate the ultraviolet radiation and its degradation effect on the textile materials. With careful and detailed study of this case we can save time, energy and money. In this study, fabric samples, which is used in outdoor applications, exposed artificially to the accelerated ultraviolet ray. Fabric sample was an industrial technical fabric composed of high tenacity nylon 66 yarns. The fabric is usually used as conveyor belt in the industries. The fabric samples were exposed to seven different exposure times in a UVC chamber. Different experiments were then carried out on the samples such as; cyclic tensile test, moisture absorption and FTIR. The significance of differences was checked with software and using ANOVA and LSD methods. The tensile tests were carried out in three different directions i.e. warp, weft and bias (45°) directions. Considering the low stress case and using appropriate equations, the shear modulus of the fabric was calculated. Shear modulus plays an important role in the application of the fabrics in conveyor belts. Other properties of the fabric, such as primary and secondary modulus, the tensile work and recovery work, total strain and remain strain were also analyzed. The results showed that the shear modulus reduces in the early stages (up to 4 hours) of the UV radiation because of breaking the links and increase in amorphous regions. However, after this early stage the shear modulus starts to increase. The FTIR analysis revealed that the reason for this may be due to formation of new links by free radicals and increasing the crystalline region. As the radiation increases (above 15 hours) the shear modulus takes decreasing trend and tends to fall again. In this case, the speed of distraction overcomes to the speed of formation of bonds and deterioration in shear modulus observes. Key words: UV radiation, nylon 66 fabric, bias samples, cyclic loading, shear modulus, tensile work, initial modulus.