Predicting the behavior of geotextiles made of polyesters and polypropylene fibers is described by differential equations derived from mechanical models. Thereby, we describe the behavior of geotextiles up to the elastic limit. The elastic limit represents the permissible load which the geotextile material may be subjected to during exploitation, and without distorting its structure. The elastic limit is defined by analyzing the stress-strain curve of analyzed geotextiles. Nonwoven geotextile materials of polyester and polypropylene fibers with surface mass of 150, 200, 250, 300 and 500g/m(2) were used as experimental material.