The content of dodecyl mercaptan (TDDM) was adjusted to prepare the polybutadiene-g-(styrene-acrylonitrile-glycidyl methacrylate) (ABS-g-GMA) core-shell particles with polybutadiene (PB) as core and styrene-acrylonitrile-glycidyl methacrylate copolymer as shell. The grafting test demonstrates that the grafting degree and grafting efficiency of core-shell particles decrease with the addition of TDDM. DMA results show that TDDM decreases the crosslinking degree of PB phase and improves its cavitation ability. The yielding stain decreases and elongation at break increases for ABS-g-GMA with increase of the TDDM content. TEM results show that TDDM has no adverse influence for the dispersion of ABS-g-GMA particles in poly(butylene terephthalate) (PBT)and polycarbonate(PC) blends. Mechanical tests indicate that ABS-g-GMA particles show excellent toughening effect on PBT/PC blends. TDDM has positive influence on the toughening of PBT/PC blends for ABS-g-GMA particles and TDDM makes the impact toughness and break strength of the blend improve.