Microwave-assisted direct conversion of cellulose into HMF in ionic liquids catalyzed by ZrCl4 has been investigated in search of an efficient and environment-friendly process. Firstly, some representative metal chlorides were used to catalyze the conversion of glucose into HMF, and it was demonstrated that ZrCl4 was superior to other catalysts. Then direct conversion of cellulose into HMF was catalyzed by ZrCl4 under microwave irradiation (MI). Under optimal conditions, a high HMF yield up to 51.4% was obtained from cellulose in 3.5 min under MI at 400 W. Controllable experiments indicated that both ionic liquids, MI and ZrCl4 showed synergetic effects on the efficient conversion of cellulose into HMF. This work provides a meaningful method for the conversion of carbohydrates into fine chemicals.