Objective:To construct the μ-Myc-pIRES2-EGFP plasmid and investigate its expression in CHO. Methods:μ gene was tagged with a 10-residue Myc epitope through PCR. Then the μ gene with Myc epitope was inserted into pIRES2-EGFP to form μ-Myc-pIRES2-EGFP recombinant eukaryotic plasmid. The μ-Myc-pIRES2-EGFP plasmid was transfected into CHO using Lipofectamine2000. The expression of μ-Myc-pIRES2-EGFP was examined by the fluorescence microscopy and Western blot. Results:The sequence of μ opioid receptor with Myc epitode was inserted into pIRES2-EGFP and confirmed by sequencing. High expression of EGFP and μ gene with Myc epitope was detected in CHO after μ-Myc-pIRES2-EGFP plasmid transfection. Conclusions:μ-Myc-pIRES2-EGFP was cloned correctly and expressed in high level in CHO cells.