Aberrant DNA methylation is now recognized as an important epigenetic alteration occurring early in human cancer.The typical pattern appears to involve reduced expression of maintenance DNA methyltransferase (DNMT1).Thus the selective DNMT1 inhibitors could be new addition to cancer therapeutic agents.In the course of our screening for the small moledules inhibiting DNMT 1,a ftmgal strain F06012 with potent inhibitory activity was selected.The activity compound was purified from ethyl acetate extract of microoganism and purified by C 18 Column chromarography and HPLC,and was identified patulin and gentisaldehyde by spectroscopic methods of ESI-MS,1H-NMR and 13C-NMR.Patulin and gentisaldehyde showed inhibitory activity of DNMT1 with an 99.8%,85.6% of 40ug/ml.