Background: Circular RNAs(circRNAs) belong to non-coding RNAs and widely expressed in a variety of cell species, including cancers. However, the function and mechanism of circRNAs in colorectal cancer (CRC) has not been well investigated. Methods: Microarray data of CRC from Gene Expression Omnibus (GEO) database was used to obtain DEGs. QRT-PCR and western blot assay were performed to determine the mRNA and protein levels of multiple genes, respectively. Cell growth and apoptosis assay were conducted to measure CRC cell proliferation and apoptosis, respectively. Luciferase assay was utilized to confirm the direct interaction between hsa_circRNA_000166 and miR-326. Results: We downloaded and analyzed the circRNA expression profile of CRC from the GEO database and identified 181 differentially expressed circRNAs between 10 pairs of CRC and adjacent normal tissues. Interestingly, we observed that the expression of hsa_circRNA_000166 was the top increased among these circRNAs. Then, we confirmed an upregulation of hsa_circRNA_000166 in CRC tissues and cell lines and observed that higher expression of hsa_circRNA_000166 was associated with poor 5-year survival rate of patients with CRC. Cell growth and apoptosis assay revealed that hsa_circRNA_000166 regulated the cell growth and apoptosis in CRC cell lines. Furthermore, we identified that hsa_circRNA_000166 targeted miR-326/LASP1 pathway using bioinformatic analysis and luciferase reporter assay. Finally, overexpression of miR-326 could sufficiently rescued the aberrant cell growth and apoptosis in CRC cell lines. Conclusion: Taken together, our results indicated that downregulation of hsa_circRNA_000166 inhibited the cell growth and facilitated apoptosis during CRC development by sponging miR-326 / LASP1 pathway.