Atrial fibrillation (AF) is one of the most common clinical cardiac arrhythmias. This study was done to screen differentially expressed circular RNAs (circRNAs) in human monocytes from patients with AF and healthy controls using microarray, and preliminarily explore the role of circRNAs in the development of AF. The expression of circRNAs in peripheral blood monocytes of 4 AF patients and 4 healthy donors was detected by chip technology and validated by qRT-PCR. Differentially expressed genes were screened out. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to identify the function of differentially expressed genes and related pathways. Potential connections between circRNAs and miRNAs were explored by using Cytoscape. 120 differentially expressed circRNAs (FC≥2, P<0.05) were preliminarily screened by circRNA microarray, of which 65 were up-regulated and 55 down-regulated. All of 4 upregulated circRNAs (circRNA_0031, circRNA_1837, circRNA_5901 and circRNA_7571) and 3 out of 4 downregulated circRNAs (circRNA_5801, circRNA_7386 and circRNA_7577) were randomly confirmed by RT-PCR. GO and KEGG analysis suggested that differentially expressed circRNA-related genes are mainly involved in inflammation, immunity, and signaling transduction. CircRNA_7571, circRNA_4648, circRNA_4631 and circRNA_2875 were the first 4 circRNAs with the most binding nodes in the co-expression network. In addition, hsa-miR-328 was the highest positively correlated miRNA in the networks. Our findings demonstrated that there were differentially expressed circRNAs in human monocytes from AF patients. circRNA_7571, circRNA_4648, circRNA_4631 and circRNA_2875 were the first 4 circRNAs with the most binding nodes in the co-expression network. hsa-miR-328 was the largest node that interacted with circRNAs in the co-expression network. circRNAs-hsa-miR-328 network may play a critical role in the pathophysiology and mechanism of AF.