This study was conducted to investigate the effects of Ephedra sinica extracts (ESE) on Aspergillus flavus growth, AFB 1 production and O-methyltransferase A (Omt-A) gene expression. The following various extracts such as Ethanol (EtOH), Ethanol: water (EtOH: H 2 O 1:1, v/v), Methanol (MeOH), and Methanol: water (MeOH: H 2 O 1:1, v/v) at concentration of 1.0, 2.0, 3.0, 4.0, and 5.0% have been used. AFB 1 production and gene expression were measured using HPLC and real time PCR, respectively. Our findings demonstrated that all ESE has significant inhibition (73.3-94.6 %) for Aspergillus flavus growth based on the dose. Production of AFB 1 was markedly decreased or totally inhibited within range of 10-99.3% depends on extract type. Supported the effect of ESE at concentrations of 1-5% were suppressed significantly (P<0.05) on aflatoxin (Omt-A) gene expression. The nucleotides sequence of Ephedra plant was submitted in GeneBank under accession number KY310531.1. These outcomes might be used to control the growth of toxigenic fungi and to inhibit the following contamination of feed, food, and agricultural supplies by carcinogenic aflatoxins.