Objective:To study the protective effect and mechanism of pyrroloquinoline quinine(PQQ) against UVA induced human skin fibroblasts. Methods:Human skin fibroblasts were cultured in 6-well plate in vitro with an equal number of cells(104~106 per well). HSF exposed to UV irradiation at a dose of 9 J/cm2. Pyrroloquinoline quinine(50,100,200 ng/ml) and 8-methoxypsoralan (80 ng/ml) were added into the cell culture medium before and after the irradiation. 8-MOP was used to enhance UVA absorption. After 72 hours of irradiation, SA-β-Gal staining was performed to evaluate the senescence state,change of mitochondria membrane potential was examined by JC-1 staining using fluorescence microscope,JC-1 staining was also used to test mitochondria membrane depolarization by flow cytometry(FCM),and real-time PCR was used to determine mRNA expression of senescence-associated gene of mmp1,mmp3. Results:Cells cultured with lower dosage PQQ (50 ng/ml) exhibited negative SA-β-Gal staining. JC-1 staining showed the change of mitochondria membrane potential was reversed by lower dosage PQQ (50 ng/ml). Mitochondria membrane depolarization was relieved lower dosage PQQ(50 ng/ml). Meanwhile,the gene expression of senescence-associated signals of mmp1,mmp3 decreased in PQQ group compared with control group. Conclusion:Pyrroloquinoline quinine can protect human skin fibroblasts from aging induced by UVA irradiation via mitochondria pathway.