Abstract: SIOC0426,N-(4-bromophenyl)-2-(4,6-dimethoxy-2-oxypyrimidine-)-6-chlorine-benzyl-amine,is a selectivity novel herbicidal compound developed in China.Bioassay results showed that SIOC0426 had good activity to early postemergence of weeds,and was safety to the cotton seedling.The selectivity coefficient of SIOC0426 between the cotton and Digitaria sanguinalis and Amaranthus retroflexus,were 3.534 and 4.299,respectively.It could control important grass and broadleaf weeds,as well as sedge weed.The most suitable application time was 1 to 2-leaf stage of the targeted weeds.The results from different spot trials in cotton showed that the total weeds controlling efficacy was 73.1%~87.6% at the dosage of 90~120 g/hm2.