Sulfonylurea herbicides have been widely used because of their low application rates, good crop selectivities and low mammalian toxicities. However, some sulfonylureas might persist unfavourably in the environment with residual problems. In order to look for ecologically safer and environmentally benign sulfonylureas, and on keeping the pyrimidine ring being monosubstituted, 15 novel C5-monosubstituted benzenesulfonylurea compounds were synthesized. The structures of all the compounds synthesized were confirmed by elemental analysis and 1H NMR. Preliminary herbicidal activities of these new sulfonylurea compounds were determined by ALS screening (in vitro) and pot bioassay experiments(in vivo). The herbicidal results show that some novel sulfonylureas are comparable to commercial Foramsulfuron and Monosulfuron.