On the basis of gas chromatography(GC) coupled with a short capillary column and an electron capture detector(ECD), a simple and rapid method for the determination of five haloacetic acids(HAAs) in drinking water was developed by the optimization of derivation conditions and the modification of gas chromatographic program. HAAs formation potential(HAAFP) of the reaction of humic acid with chlorine was determined via this method. The major advantages of the method are the simplicity of chromatographic temperature program and the short run time of GC. Dichloroacetic acid(DCAA) and Trichloroacetic acid(TCAA), which were detected in the determination of HAAFP, were rapidly formed in the first 72 h of the reaction of humic acid with chlorine. HAAFP of the reaction of humic acid with chlorine increased with the increase in the concentrations of humic acid and chlorine. The average HAAFP of the reaction of humic acid with chlorine was 39.9 μg/mg TOC under the experimental conditions. When the concentration of humic acid was 4 mg/L, the concentration of HAAs, which were produced in the reaction of humic acid with chorine, may exceed MCL of 60 μg/L HAAs as the water quality standards for urban water supply of China and the first stage of US EPA disinfection/disinfection by-products(D/DBP) rule; when the concentration of humic acid was 2 mg/L, the concentration of HAAs may exceed MCL of 30 μg/L HAAs for the second stage of US EPA D/DBP rule. When humic acid was reacted with chlorine dioxide, only DCAA was detected with a maximum concentration of 3.3 μg/L at a humic acid content of 6 mg/L. It was demonstrated that the substitution of chlorine dioxide for chorine may entirely or partly control the formation of HAAs and effectively reduce the health risk associated with disinfected drinking water. On the basis of gas chromatography (GC) coupled with a short capillary column and an electron capture detector (ECD), a simple and rapid method for the determination of five haloacetic acids (HAAs) in drinking water was developed by the optimization of derivation conditions and the modification of gas chromatographic program. HAA formation potential (HAAFP) of the reaction of humic acid with chlorine was determined via this method. The major advantages of the method are the simplicity of a chromatographic temperature program and the short run time of GC. Dichloroacetic acid (DCAA) and Trichloroacetic acid (TCAA), which were detected in the determination of HAAFP, were rapidly formed in the first 72 h of the reaction of humic acid with chlorine. HAAFP of the reaction of humic acid with chlorine increased with the increase in the concentrations of humic acid and chlorine. The average HAAFP of the reaction of humic acid with chlorine was 39.9 μg / mg TOC under the experimental conditions. When th e concentration of humic acid was 4 mg / L, the concentration of HAAs, which were produced in the reaction of humic acid with chorine, may exceed MCL of 60 μg / L HAAs as the water quality standards for urban water supply of China and the first stage of US EPA disinfection / disinfection by-products (D / DBP) rule; when the concentration of humic acid was 2 mg / L, the concentration of HAAs may exceed MCL of 30 μg / L HAAs for the second stage of US EPA D / DBP rule. When humic acid was reacted with chlorine dioxide, DCAA was detected with a maximum concentration of 3.3 μg / L at a humic acid content of 6 mg / L. It was demonstrated that the substitution of chlorine dioxide for chorine may entirely or partly control the formation of HAAs and effectively reduce the health risk associated with disinfected drinking water.