Abstract: In the course of screening novel pesticides or leading compounds from microorganisms,an actinomyces strain 70014 was isolated from the soil sample collected in an island near Shanghai.The metabolites of the strain showed high herbicidal activity to various broad-leaved and gramineous weeds.According to its culture characters,biochemistal characters,the consist of cell wall and 16S rDNA sequence,the strain was identified as Streptomyces griseolus.The herbicidal activity compounds were isolated using solvent extraction,silica gel chromatograph and preparative HPLC.One main activity compound was purified.By the means of physico-chemical properties and spectroscopy analyses,the structure was elucidated as:2-2-(3,5-dimethyl-2-oxo-cyclohexyl)-6-oxo-tetrahydro-pyran-4yl-acetamide.The structure appeared the same as the antibiotic A-75943,which was isolated from S.sp.SANK6129 with bone resorption inhibition activity.But the herbicidal activity of this compound was firstly reported in this study.In germination inhibition experiments,the compound could inhibit both root and shoot growth at a concentration of 1 mg/L.In the pot tests,at a dose of 75 g/ha,SPRI-70014 provided effective control over most broad leaved weeds at the effect of 96% －100%.At the dose of 150 g/ha,the compound showed effective control over gramineous weeds as well.The fresh weight ED90 against Leptochloa chinenesis (L.) Ness,Eleusine indica (L.) Gaertn.,Amaranthus retroflexus L.,white Eclipta prostrate L.was 143.29,146.94,80.88 and 2,respectively.Crop safety experiments showed that the compound had no harmful effect on peanut and wheat plants,at the dose as high as 2 000 g/ha.