Pineapple (Ananas cosmosus (L) Merr) which belongs to the Bromeliaceae family is a tropical and subtropical plant that is widely available in Indonesia. The shape of pineapple leaves is like a sword that tapers at the end with a blackish green color and sharp thorns on the side of the leaves. The fiber of Pineapple leaf consists of cellulose and non cellulose which is obtained by removing its outside layers mechanically. The research results of pineapple leaves chemical properties showed that cellulose content was between 69.5% - 71.5%, lignin level was between 4.4% - 4.7%, pectin level was 1.0% -1.2%, fat content and wax was 3% -3.3%, ash content was between 0.71% - 0.87%, while pentosan content was between 17.0% -17.8%. Pineapple leaf fiber has the potential to be used as an alternative to textile raw material by reducing the lignin content in the pineapple leaf fibers through the delignification process. In this research, pineapple leaf fiber extraction process was carried out in five stages were preparation stage, deliginification stage, washing stage, neutralization stage and preservation stage. The preparation stage is to prepare the raw material by removing the flesh of the pineapple leaf skin until white fiber is seen then slowly the fiber is taken. The second stage is the delignification stage of pineapple leaf fiber soaked in 2 – 7% NaOH solution with and without stirring using a magnetic stirrer. The third stage is the washing stage by rinsing the fiber of pineapple leaves using distilled water to remove the remaining solvents and impurities in the fiber. The next process is neutralization conducted by boiling pineapple leaf fiber at a temperature of 100 ° C for 2 hours. Then the preservation stage is done by drying the pineapple leaf fiber until it reaches its constant weight. In this experiment, the most optimal pineapple fiber result was pineapple fiber in 4% NaOH concentration, immersion temperature 80 ° C, and 300 rpm stirring rate with lignin content of 0.3%; pore size 18.30 µm; and tensile strength of 10.83 g / Tex.