Fifteen N’-(substituted pyrimidin-2-y1)-N-substituted phenoxyacetyl thioureas were synthesized and tested for biological activities. All of them are new compounds and their structures were confirmed by IR. IHNMR. MS and elemental analysis. Some of the target compounds showed excellent inhibitory activities against root and stalk of dicotyledon plant (such as radish). and selective on monoctyledon plant (such as rice). Fifteen N ’- (substituted pyrimidin-2-y1) -N-substituted phenoxyacetyl thioureas were synthesized and tested for biological activities. All of them are new compounds and their structures were confirmed by IR. IHNMR. MS and elemental analysis. Some of the target compounds showed excellent inhibitory activities against root and stalk of dicotyledon plant (such as radish). and selective on monoctyledon plant (such as rice).