The prevention of bacterial infection is becoming more and more important in clinical medicine. Ionic liquids (ILs) can change the structure in an almost infinite way to actively antagonize pathogenic microorganism strains. The current biological materials of skin dressings inevitably have the shortcomings of single drug delivery form and low drug loading, which limit the practical application of skin dressings. Therefore, it is particularly important to develop drug delivery forms that can meet different conditions. The addition of ILs into crosslinked microneedle (MN) patches is a novel design scheme of MNs. The broad-spectrum antibacterial properties of imidazolium salt ILs ensure that the wound skin is sterile after the use of MN patches on the skin to open channels for drug delivery. In this study, imidazole IL monomers with different carbon chain lengths and the corresponding IL-MN patches were designed and synthesized. By comparing the antibacterial properties of four imidazolium salt IL monomers with different carbon chain lengths and the corresponding ionic liquid microneedle patches, we found that the antibacterial properties of IL monomers and IL-MN patches increased with the increase of substituent carbon chain lengths. Imidazole IL monomers have excellent antibacterial properties, which may be caused by the electrostatic interaction between the cations in the IL monomers and the anions in the bacterial membrane and the hydrophilic and hydrophobic interactions between the IL monomers.