The bioavailability of bound residue(BR) derived from 14 C-labeled chlorsulfuron in soil and effect of themain components of the BR on growth of rape( brassica napus) and rice( Oryza sativa L. ) were investigated. Theresults showed that the BR with the concentration of 0.28 and 0.56 nmol/g air-dried soil, which was calculated byspecial radioactivity of 14C-labeled chlorsulfuron parent compound, resulted in significant depression effect on growthof rape seedling. It was assured that the main components(2-amino-4-methoxyl-6-methyl-1,3,5-triazine, 2-amino-4-hydroxyl-6-methyl-1,3,5-triazine, and 2-chloro-benzenesul-fonamide) of the BR did not inhibit the growth of rape andrice. LC-MS analysis demonstrated that the parent compound previously bound to the soil matrix could be againreleased and transformed into methanol-extractable residue during the course of rape growth. It was concluded thatthe molecular leading to the phytotoxicity to rape and rice in the BR is still the parent compound.