Abstract: The influence of dispersants, flame retardants，and carriers on the burning rate of ABS masterbatch was studied. It was found that the dispersant accelerated the combustion, the burning rate of ABS could be decreased by flame retardant and CPE carrier. A slowly-burning grade of ABS masterbatch was developed by optimizing the formulation design. When being applied to ABS products, UL 94 HB standards and a uniform surface color were achieved. The retention rate of impact strength and tensile strength were above 90 %.