Polyesrer fibers are used in several applications like the clothes and industrial textile because of its attributes such as the great mechanical properties, good resilience, chemical neutrality and temperature resistance. But when dyeing the polyester fiber especially the black or other dark colors, gaining a very deep color is difficult. Polyester fibers reflect most of the light from their surface which is because of their natural high refractive index (n= 1.725) and it prevents to gain a high color shade. The purpose of this study is to achieve a methodology for increasing of the color depth in the polyester fabrics. In this methodology, the particles are thrown to the textile surface to increase the surface roughness. To do so, a collection was designed and the particles were thrown by the spray gun. Some samples were provided and studied upon to evaluate the effect of the particles kind, particles mesh, air pressure, particles spray angle, distance of the spray gun from the fabric and the spraying time on the roughness of the fabric surface. To study the operation effect, the surface of the fibers were photographed by the microscope and also the value of L* and the reflection in the samples were measured by the spectrophotometer. According to the results, the particles spray operation caused the increase in the roughness of the fibers surface and the L* value decreased. The effect of the above said variables on the reflection value before and after dyeing were studied. Keywords: polyester fibers, color depth, sandblasting operations