Objective To investigate the effect of overexpression of circRNA La-associated protein 4 (circ_LARP4) on malignant biological behaviors of MCF-7 breast cancer cells. Methods MCF-7 cells were transfected with circ_LARP4 plasmid pcDNA-circ_LARP4, and the expression of circ_LARP4 was detected by real-time quantitative PCR(qRT-PCR). After circ_LARP4 overexpression, CCK-8 assay was used to detect the proliferation of MCF-7 cells, and mRNAs of ki67, p21, inducible nitric oxide synthase (iNOS) and interleukin-1β (IL-1β) were detected by qRT-PCR. The bullet volume of tumor stem cells was observed under microscope, and the number of invaded cells was detected by TranswellTM assay. The expressions of octamer binding transcription factor 4(OCT4), SRY-related high-mobility-group box gene 2 (SOX2), vascular endothelial growth factor (VEGF), epithelial cadherin (E-cadherin) and neural cadherin (N-cadherin) were detected by Western blot. The levels of iNOS and IL-1β in the supernatant of MCF-7 cells were detected by ELISA. Results Compared with the control group, circ_LARP4 overexpression group showed an upregulation in the expression of circ_LARP4, decreased cell proliferation, and down-regulated expression of ki67. It also reported the up-regulated expression of p21, smaller tumor stem cell bullet size, and decreased the expression of OCT4 and SOX2, together with the decreased number of invaded cells, decreased expression of VEGF and N-cadherin, increased expression of E-cadherin, and decreased levels of iNOS and IL-1β. Conclusion Overexpression of circ_LARP4 inhibits the proliferation, invasion and stem cell-like characteristics of MCF-7 breast cancer cells, and down-regulates the levels of iNOS and IL-1β.