Objective:To investigate the effect and potential mechanism of miR-199a-5p on the radiosensitivity of cervical cancer CaSki cells.Methods:Cervical cancer CaSki cells were cultured in vitro. MiR-199a-5p mimics (miR-199a-5p mimics) were transfected into cervical cancer CaSki cells (miR-199a-5p group) with liposome by Lipofectamine 2000. CaSki cells transfected with mimics control were used as negative control (NC group) and non transfected CaSki cells were used as blank control (control group). After X-ray irradiation, real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression of miR-199a-5p in cells of each group. The effects of miR-199a-5p on radiosensitivity and apoptosis of CaSki cells were detected by clone formation assay and flow cytometry apoptosis assay. Bioinformatics software was used to predict the target gene of miR-199a-5p. Double luciferase reporter gene assay and Western blot were used to verify the targeting relationship between miR-199a-5p and thyroid hormone receptor interaction factor 4 (TRIP4). Results:The expression of miR-199a-5p in miR-199a-5p group was significantly higher than that in control group ( P<0.05). After X-ray irradiation, the expression of miR-199a-5p was more obvious ( P<0.05); Overexpression of miR-199a-5p could reduce the clonogenic ability and promote the apoptosis of CaSki cells ( P<0.05); Overexpression of miR-199a-5p could further reduce the clonal formation and promote the apoptosis of irradiated cells ( P<0.05); Double luciferase reporter gene experiment and Western blot confirmed that miR-199a-5p could target and negatively regulate TRIP4. Conclusions:miR-199a-5p can increase the radiosensitivity of cervical cancer CaSki cells by negatively regulating the expression of TRIP4.