Multi-located field and the joint action of the herbicide combination of mefenacet and pyrazosulfuron-ethyl trails were conducted in 2001to determine the selectivity and weed con-trol efficacy of 41%Kechaduo in transplanted rice,the results were as follows:Excellent weed control performance were achieved when applied at the above-mentioned application timing,with an average control percentage higher than 85%against barnyardgrass and almost complete control of various annual broadleaf weeds sedges including Barnyardgrass,Difformed Galingale,Eleocharis yokoscensis(Franch.et sav)Tang et Wang,Korsakow Monochoria oldworld Arrowhead,Oriental waterplantain,Rush-like Blurush,Distinct Pondweed,ect 41%.Kechaduo gave excellent crop safety when used at 5~10days after transplanting 0~2leaf stage of barnyardgrass within 492~615g.ai./hm 2,various application method is applicable,such as soil-based instant granule method.Fertilizer-based instant granule method.It is one of the best one-shot rice herbicides for using in transplanted rice of northeast China.