The objective of the study was to explore the role of SDC1 in breast cancer cells. Our study also investigated the regulatory relationship between SDC1 and the microRNA (miRNA) miR-335-5p as well as the impact of these two genes on the progression of breast cancer. Bioinformatic approaches were employed to analyze the differentially expressed messenger RNAs (mRNAs) and miRNAs (DE-mRNAs and DE-miRNAs) in breast cancer tissue. Then mRNA SC1 was obtained. Differentially downregulated mRNAs were intersected with target miRNAs predicted by databases, and miR-335-5p was determined as the study object. Quantitative reverse transcription polymerase chain reaction was applied to assess the expressions of SDC1 and miR-335-5p in each cell line. Next, Western blot assay was conducted to detect the protein level of SDC1 and dual-luciferase assay was performed to verify the binding relationship between miR-335-5p and SDC1. Finally, we conducted methyl thiazolyl tetrazolium (MTT), colony formation, and Transwell assays and flow cytometry to further investigate the impacts of SDC1 and miR-335-5p on the progression of breast cancer. SDC1 was significantly highly expressed while miR-335-5p was remarkably lowly expressed in human breast cancer. Silencing SDC1 in breast cancer blocked the proliferation, migration and invasion of the cells. In breast cancer, SDC1 was a target gene of miR-335-5p and silencing miR-335-5p notably increased SDC1 expression. Compared with the silence of miR-335-5p, simultaneous silences of miR-335-5p and SDC1 significantly reduced the proliferative, migratory and invasive abilities of breast cancer cells. The result revealed the interaction between miR-335-5p and SDC1 in the progression of breast cancer, which may contribute to the treatments for this cancer.