Projective: HIF-1α is highly expressed in the triple negative breast cancer cell line (MDA-MB-231), which is lack of the expression of ER,PR and HER2 and exhibits high invasive and metastatic ability. Previous study detected that siRNA targeting HIF-1α in MDA-MB-231 restrained the cell growth and the abilities of immigration and invasion, and promoted apoptosis. UCH-L3 protein was found to be one of the differential proteins detected by Bidirectional gel Electrophoresis and Proteomics in the cells with HIF-1α siRNA cells comparing to no-siRNA cells. The objective of this study is to probe the effect of UCH-L3 on the biological behaviors of the triple negative breast cancer cell line (MDA-MB-231).Methods: Over or blocking expressions of UCH-L3 were established by the transfections with lentiviral constitutive vector and siRNA targeting UCH-L3 respectively. Real time quantitative PCR and Western blot or Co-ip were used to detect the mRNA and proteins. CCK8, and clone formation assays were to evaluate the cell growth and clonality. Matrigel Transwell and Would Scratch assay were used to estimate the cell invasion and mobility. Results:The over-expression of UCH-L3 inhibited the cell growth and clonality, weaken the abilities of cell immigration and invasion, and lowered the expression of free and ubiquitined HIF-1α in MDA-MB-231 cells with lentiviral vector comparing to those in the cells with control vector. Application of proteolytic enzyme inhibitor, MG132 increased the protein level of UCH-L3 but still decreased the protein level of HIF-1α in the cells with UCH-L3 over-expression. Blocking UCH-L3 expression by siRNA technique increased the expression of HIF-1α properly. Conclusion: high expression of UCH-L3showed an inhibitory effect on the biological behaviors of triple negative breast cancer cell and negative effect on HIF-1α expression, implying that UCH-L3 likely to be a therapeutic strategy for triple negative breast cancer.