Objective: To build the stress-induced premature senescence(SIPS) model with fibroblasts after repeated exposures to sub-toxic doses of ultraviolet B(UVB), and observe the expressions of senescence-associated biomarkers,senescence-associated signals including p53,p16,p21,sirtuin 1(SIRT1),as well as senescence-associated miRNAs such as miR-34c. Methods: Skin fibroblasts were repeatedly exposed to UVB irradiation at a dose of 10 mJ/cm2 for 5 times. After 5 days of treatment,SA-β-Gal staining was performed to evaluate the senescence state,flow cytometry to analyze cell cycle,and real-time quantitative PCR to determine mRNA expression of senescence-associated signals including p53,p16,p21,SIRT1 and miR-34c. Western blot was performed to detect the expression of p53,p21,p16 and SIRT1. Results: Compared with the control group,strong positive SA-β-Gal was observed in SIPS group,(94.72 ± 2.08)% in SIPS group compared with (8.13 ± 1.92)% in control group(P < 0.05). Most cells were arrested in G1 phase,(52.96 ± 1.76)% in control group compared with (77.31 ± 2.05)% in SIPS group(P < 0.05). Meanwhile,the expression of senescence-associated signals including p53,p16,p21,SIRT1 significantly increased after UVB exposure (0.74 ± 0.23,1.06 ± 0.23. 0.86 ± 0.13,0.74 ± 0.25 in control group while 1.84 ± 0.55,20.25 ± 2.34,16.7 ± 3.94,2.15 ± 0.22 in SIPS group,P < 0.05),so as to that of senescence-associated miRNAs such as miR-34c (0.93 ± 0.09 for miR-34c-3p and 1.03 ± 0.03 for miR-34c-5p in control group while 2.08 ± 0.19 for miR-34c-3p and 12.28 ± 1.64 for miR-34c-5p in SIPS group,P < 0.05). Western blot showed that p53,p21,p16 and SIRT1 protein expression significantly increased in SIPS group compared with those in control group,and the difference was statistically significant(P < 0.05). Conclusion: The expression of miR-34c increases after repeated exposures to sub-toxic doses of UVB in skin fibroblasts,and it works as a positive feedback regulation to P53 while not inhibiting SIRT1.