The work to find the compounds which can adsorb methylene blue (MB) for the treatment of textile wastewater, that is essential in the current period. In this study, rice husk ash was used for MB adsorption under conditions of pH ranging from 6-7-8-9, the mass of rice husk ash ranging from 0.05-0.1-0.25-0.5-0.75-1.0g and stirring time ranging from 20-40-60-80-100 minutes. The concentration of MB solution is fixed at 50 ppm, the volume of the used solution was 25ml at the room temperature. The results showed that when adding 0.1g of rice husk ash with a volume of porous hole of 0.005 cc/g, diameter of porous hole = 2.320e + 01 A into the solution of MB of 50ppm for 60 minutes at pH of 8, the maximum adsorption capacity of rice husk ash reached 11.1mg/g. This shows the ability to utilize rice husk ash, an agricultural waste, to treat wastewater.