NOVELTY - An aqueous solution of 12% urea/7% sodium hydroxide is frozen to -12 degrees C to -15 degrees C, and modified carboxymethyl cellulose of bamboo leftover and beta -cyclodextrin are added to aqueous solution and stirred. Epichlorohydrin is added to mixture, ultrasonically degassed, sealed, maintained at room temperature for 36-48 hours, washed, soaked and dried, to obtain environmentally-friendly porous modified bamboo leftover cellulose/ beta -cyclodextrin hydrogel.    USE - Preparation of bamboo leftover environmentally-friendly hydrogel used for fertilizer material, controlled drug delivery material and absorption of cationic dye molecules (claimed).    ADVANTAGE - The method enables preparation of bamboo leftover environmentally-friendly hydrogel under mild reaction condition by simple method.    DETAILED DESCRIPTION - Bamboo leftover is washed, dried and crushed, to obtain bamboo slag powder. Distilled water is added to bamboo slag powder, de-enzymed, and the pH is adjusted, bleached, filtered, washed and dried, to obtain pretreated bamboo leftover fibers. Alkali solution is added to bamboo leftover fibers, alkalized, washed and dried and hemicellulose is removed, to obtain bamboo leftover cellulose. Bamboo leftover cellulose is provided to reactor, and aqueous solution of isopropyl alcohol and hydrogen peroxide solution are added to reactor, mixed, and sodium hydroxide solution is added to mixture and alkalized. A solution (s1) of sodium chloroacetate is added to alkalized mixture, heated, alkalized, and sodium hydroxide solution and solution (s2) of sodium chloroacetate are further added to mixture, alkalized and etherified. The solution (s1) of sodium chloroacetate and solution (s2) of sodium chloroacetate comprises alcoholic solution of sodium chloroacetate. After completion of etherification, the mixture is cooled to room temperature, and supernatant is removed, and methanol is added, washed with ethanol and dried, to obtain modified carboxymethyl cellulose of bamboo leftover. An aqueous solution of 12% urea/7% sodium hydroxide is frozen to -12 degrees C to -15 degrees C, and modified carboxymethyl cellulose of bamboo leftover and beta -cyclodextrin are added to aqueous solution and stirred. Epichlorohydrin is added to mixture, ultrasonically degassed, sealed, maintained at room temperature for 36-48 hours, washed, soaked and dried, to obtain environmentally-friendly porous modified bamboo leftover cellulose/ beta -cyclodextrin hydrogel.