Abstract: Objective:To obtain the core cDNA sequence of rat tyrosine hydroxylase（TH） and synthesize THmRNA in vitro. To observe the expression of THmRNA in eukaryotic cell. Methods: The full length of cDNA from rat TH was used as template and the specific oilgonucleotide primers were designed for Polymerase Chain Reaction（PCR）. An eukaryotic vector, plasmid pcDNA3.1/TH, was constructed, then Synthesizing THmRNA in vitro. The newly Synthesized THmRNA was transfected in vitro to the cultured NIH 3T3 cells. The expression of TH was tested by immunocytochemistry and Western blot. Results: The expression of TH was shown in NIH 3T3 by immunocytochemistry staining and Western blot. The transfected THmRNA can express TH in cultured NIH 3T3 cells as long as 2 weeks. Conclusions: These findings suggest that THmRNA is a newly and valuable tool to the treatment for Parkinson's disease.