Soybean is one of the most important oilseed crops, and its seed oil content directly determines the economic value and industrial applicability worldwide.However, how soybean seed oil accumulation is regulated remains less understood.Here, through RNA-seq analysis and screening for the interacting proteins of a positive oil regulator GmNFYA, we identified an AP2/ERF-type transcription factor GmERFA, which acts as a negative regulator of oil accumulation. Knocking out GmERFA and its homologue by genome editing increased seed total fatty acid content, while overexpression of GmERFA leads to reduced fatty acid level in transgenic soybean. GmERFA interacts with GmNFYA to inhibit its transcriptional activation of GmbZIP123 and GmZF392, both of which promotes seed oil accumulation. The GmERFA also directly binds to the promoter regions of GmbZIP123 and GmZF392 and represses their gene expression. Through further analysis of more than 300 soybean accessions, an elite allele of ERFA with Hap3 promoter is identified to correlate with lower promoter activity, lower gene expression but higher seed oil content. The Hap3 ERFA may be selected and fixed during soybean domestication. Together, our study discovers a brake gene for oil accumulation and may function in a novel molecular network GmERFA-GmNFYA-GmbZIP123/GmZF392 at the later stage of soybean seed development. Manipulation of the gene, its elite allele and the whole pathway should benefitbreeding for high oil cultivars in soybean.