Objective：To screen out the key circRNAs that regulate the proliferation and invasion of adenocarcinoma of the esophagogastric junction（AEG） by high-throughput RNA sequencing and bioinformatics analysis，and to preliminarily explore their modes of action. Methods：RNAs were extracted from 22 pairs of adenocarcinoma of the esophagogastric junction and adjacent normal mucosa tissues. Differentially expressed genes were screened out by high-throughput RNA sequencing（sequencing depth 200×） and bioinformatics cloud platform. Meanwhile，a co-expression network and an endogenous RNA competition mechanism（ceRNA） network among circRNAs-miRNAs-mRNAs were constructed for differentially expressed genes. The construction of co-expression network of RNA maps and the negative correlation analysis of endogenous competitive RNAs were used to screen for circRNAs that may play a key role in the development of AEG，and to predict the expression of miRNAs and mRNAs which have ceRNA relationship with the circRNA. qRT-PCR and other methods were used to verify the expression of circRNA in gastric cancer tissues and adjacent tissues. Results：A total of 46553 circRNAs were predicted by high-throughput RNA sequencing，and 26 differentially expressed circRNAs were obtained after strict quality control of sequencing data（fold change ≥2 or fold change ≤0.5，false discovery rate<0.05）. Among them，10 circRNAs were up-regulated and 16 circRNAs were down-regulated. Tissue samples were analyzed by mRNA and miRNA sequencing，and the ceRNA network among circRNAs-miRNAs-mRNAs，co-expression network of RNA maps，and endogenous competitive RNA negative correlation analysis were constructed. The results showed that has_circ_0007766 was highly specifically expressed in AEG tumors，which may play a key role in the development and progression of AEG. Meanwhile，it was also found that miR4492 had binding sites with both circRNA0007766 and MET mRNA. Conclusion：The has_circ_0007766 may regulate the proliferation and invasion of adenocarcinoma of the esophagogastric junction through the ceRNA network of mir4492- and circRNA0007766-MET mRNA，which may be the key circRNA for the development and progression of AEG.