Objective: This study focused on the same split vaccine antigen system to compare the protective efficacy of two immunization strategies: intramuscular injection with aluminum adjuvant-CpG oligodeoxynucleotide (Alum-CpG) and intranasal delivery with sugar-based lipid nanoparticles (SNP). Methods: Eight-week-old female BALB/c mice were randomly assigned into different experimental groups: Alum-CpG group, SNP group, intramuscular unadjuvanted split vaccine group, and unimmunized control group. All mice received two immunizations 14 days apart. On day 14 after the booster immunization, serum and nasal lavage fluid(NLF) were collected. Antibody levels were measured by hemagglutination inhibition (HI) assay and indirect enzyme-linked immunosorbent assay. Mice were then challenged with heterologous virus A/Scotland/P2/2015(H1N1) to evaluate body weight changes, survival rate, lung viral load, and pulmonary pathological changes. Results: Under equivalent antigen doses, intramuscular administration of the split vaccine adjuvanted with Alum-CpG significantly elevated serum HI antibody titers. Following viral challenge, mice in this group achieved a 100% survival rate, accompanied by marked reductions in lung viral loads and substantial alleviation of influenza-associated inflammatory lung pathology. Although the SNP group induced detectable serum HI antibodies and secretory IgA (sIgA) responses, and conferred partial protection against influenza virus challenge, its serum HI titers, survival rates, and viral clearance capacity were all inferior to those observed in the Alum-CpG group and the split vaccine group. Moreover, higher levels of viral replication were still detectable in the lung tissues of some mice in the SNP group. Conclusion: The intramuscular vaccination strategy employing Alum-CpG adjuvant markedly enhanced both the immunogenicity and protective efficacy of the split vaccine, demonstrating superior immune-enhancing effects compared to the intranasal SNP delivery. SNP have potential as an intranasal delivery platform, but their formulation design requires further optimization to improve protective efficacy.