Fusarium crown rot (FCR) caused byFusarium pseudograminearumis one of the most serious soil-borne diseases of wheat. Among 58 bacterial isolates from the rhizosphere soil of winter wheat seedlings, strain YB-1631 was found to have the highest in vitro antagonism toF. pseudograminearumgrowth. LB cell-free culture filtrates inhibited mycelial growth and conidia germination ofF. pseudograminearumby 84.14% and 92.23%, respectively. The culture filtrate caused distortion and disruption of the cells. Using a face-to-face plate assay, volatile substances produced by YB-1631 inhibitedF. pseudograminearumgrowth by 68.16%. In the greenhouse, YB-1631 reduced the incidence of FCR on wheat seedlings by 84.02% and increased root and shoot fresh weights by 20.94% and 9.63%, respectively. YB-1631 was identified asBacillus siamensisbased on thegyrBsequence and average nucleotide identity of the complete genome. The complete genome was 4,090,312 bp with 4357 genes and 45.92% GC content. In the genome, genes were identified for root colonization, including those for chemotaxis and biofilm production, genes for plant growth promotion, including those for phytohormones and nutrient assimilation, and genes for biocontrol activity, including those for siderophores, extracellular hydrolase, volatiles, nonribosomal peptides, polyketide antibiotics, and elicitors of induced systemic resistance. In vitro production of siderophore, β-1, 3-glucanase, amylase, protease, cellulase, phosphorus solubilization, and indole acetic acid were detected.Bacillus siamensisYB-1631 appears to have significant potential in promoting wheat growth and controlling wheat FCR caused byF. pseudograminearum.