Ancient civilizations have found that sunlight provided a field of vision, heat, health, and life. Beginning in the nineteenth century, it has known that sunlight was not a single stimulus, but a set of stimuli of different wavelengths (such as infrared, visible, and ultraviolet (UV) radiation). Ultraviolet rays have a very small fraction in the spectrum of the sun's spectrum but can affect all living organisms and their metabolism. Ultraviolet rays cause destructive effects such as cancer cells, premature aging and skin wrinkles. Because of the harmful effects of UV rays, it is important that how to protect them. There are several methods to protect textiles from UV rays, each of them leads to good and excellent protection. One of these methods is the use of dyes that can be effective on protection against ultraviolet rays by the fabric, depending on the concentration of dye and the absorption of dye in the UV region. The method of measuring the protection factor of textiles against ultraviolet rays through transmission using a spectrophotometer is a suitable method for measuring this factor. In this study, using a light source that simulates sunlight, the amount of waves transmitted from the textiles is evaluated based on the color change of a sensitive light sample that is tested under the textile. Since the color change of a light-sensitive sample is a function of the intensity of the ray transmitted from the textile being tested, the relationship between the color change and the textile protection factor is used by measuring the color coordinates of these samples. In this study, in order to protect the textile against UV rays, fluorescent dye was used as an ultraviolet absorber and the polyester fabric was dyed with this dye. For this purpose, to study the protection of polyester containing fluorescent dye, woolen fabrics were dyed with basic dye as a sample of light sensitive. Then the polyester samples along with the wool samples were placed in Xenotest device and after different durations and different exposure intensities, the reflection and purity of the wool samples were measured and by placing them in the relevant formula, the values Polyester protection was obtained. To better analysis, the adsorption of dyeing effluents and reflection differences of polyester samples were also performed. Finally, studies have shown that fluorescent dyes, despite having good absorption in the UV region, did not provide good protection for the fabric against UV rays, contrary to expectations.