Glutathione S-transferase (GST) gene, PcgstA was cloned from the penicillin producing strain Penicillium chrysogenum, which is important for understanding the industrial fermentation process. PcgstA gene has an open-reading-frame of 840 bp in length, which is interrupted by two introns. The deduced amino acid sequence shows about 50% identity to several characterized filamentous fungi GSTs. The recombinant PcGSTA in Escherichia coli were overexpressed and purified. Enzymatic assays showed that the recombinant PcGSTA had a specific activity with 1-chloro-2, 4-dinitrobenzene of (0.159±0.031) μmol/(min·mg). It was found that the expression level of PcgstA in the penicillin producing medium supplemented with phenylacetic acid, the side chain precursor of penicillin G, was significant down regulated than that in medium without phenylacetic acid. This result suggested that PcGST may be related to phenylacetic acid metabolism in the penicillin producing strain.