Chitin treatment using different methods, including ball mill grinding, steam explosion, alkaline treatment, phosphoric acid, and ionic liquid (IL) dissolution/reprecipitation have been systematically investigated. The chitin structures were thoroughly investigated by using a series of analytical techniques, and the reactivity after each treatment was evaluated in dehydration and liquefaction reactions. The parallel studies enable direct comparisons of these methods and help to establish the structure-activity correlations. Ball mill grinding in dry mode was the most effective method, with the crystal size and the hydrogen-bond network being the two crucial factors in enhancing the reactivity. Remarkably, the yield of 3-acetamido-5-acetylfuran (3A5AF) from chitin dehydration increased to the highest amount (28.5 %) after ball mill grinding (the previous record yield was 7.5% for untreated chitin).