Poplar leaves were used as adsorbents to adsorb methylene blue. Through comparing the methods of acid modification, alkali modification and thermal modification methods, the maximum equilibrium adsorption capacity of the acid modified poplar leaves reached 342.3 mg/g. In other words, the adsorption capacity of poplar leaves treated by acid modification method was the maximum. At the temperature of about 30-50℃ and the pH value of 3, the poplar leaf adsorption modification had the best effect.