Hereby, one kind of facile carbon dots (CDs) from hydroxypropylmethyl cellulose (HPMC) has been successfully provided, which obviously emitted blue fluorescence. With the related characterizations in detail, the CDs prepared here mainly consisted of C and O, owing to the functional groups of -OH and C=O on their surfaces. Likewise, the CDs also showed multiple advantages, including excellent photostability, superior dispersity and desirable stability. Moreover, the CDs were applied for sensing ciprofloxacin due to forming complexes with ciprofloxacin, thus leading to the fluorescence quenching of CDs. This proposed method was permitted to sense ciprofloxacin in a linear range of 10 nM L -1 -90 ÎźM L -1 , suggesting that it may broaden the sensing ways for assaying ciprofloxacin.Keywords Carbon dots, assay, ciprofloxacin