Objective To investigate the role of Notch signaling in regulating the polarization of macrophages with signal regulatory protein α (SIRPα). Methods RAW264.7 cells were polarized into M1 phenotype after being treated with lipopolysaccharides (LPS) and interferon γ (IFN-γ) and into M2 phenotype with interleukin-4(IL-4). The mRNA levels of tumor necrosis factor α (TNF-α), IL-12, IL-10, mannose receptor (MR), and SIRPα were detected by real-time quantitative PCR. The protein expression level of SIRPα was detected by Western blotting. After Notch signal was activated by gene transfection or blocked by gamma-secretase inhibitor (GSI), SIRPα expression in macrophages was detected by Western blotting. SIRPα promoter region (-2615-+123) was amplified by mouse genomic DNA, and the regulatory effect of Notch activation on SIRPα was detected by reporter gene assay. Results The expression of SIRPα decreased in M1 type macrophages and increased in M2 type macrophages. Notch signaling inhibited the expression of SIRPα in macrophages, while GSI increased the expression of SIRPα in macrophages. Reporter gene assay confirmed that Notch activation significantly inhibited luciferase expression driven by SIRPα promoter fragment. Conclusion Notch signaling involves the M1-type polarization of macrophages by inhibiting the expression of SIRPα.