Abstract: Copper(II) carboxymethylcellulose was prepared with sodium carboxymethylcellulose and copper sulphate in aqueous solution. Sweetening properties of copper (II) carboxymethylcellulose in liquid hydrocarbon was studied using petroleum ether containing 96×10-6 n-pentanethiol and 16×１０-6 thiophene as a model solution. Mercaptan in the model solution could be cleaned out at 24.0h-1 space velocity at room temperature. Sweeten capacity of copper (II) carboxymethylcellulose is 925mL/g for the model solution or 1.86mmol/g for mercaptan. Copper (I) that reduced from copper(II) was found in saturated cuprum carboxymethylcellulose material by XPS. Dipentyl disulfide, the oxidation product of n-pentanethiol, was detected in the model solution after sweetening by GC-PFPD. The sweetening mechanism of copper (II) carboxymethylcellulose was confirmed as an oxidation-reduction process.