Objective To explore the association of Toll-like receptor 7, CTLA-4 gene polymorphisms and severe asthma. Methods From February 2018 to March 2020, 175 asthma patients admitted to the respiratory department of our hospital were selected as the research subjects (109 cases of mild disease and 66 cases of severe disease), and 248 cases of healthy people who were included in the outpatient physical examination of our hospital during the same period were selected as the normal control group. Toll-like receptor 7 and CTLA-4 gene polymorphisms in the above groups were determined, and the relationship between Toll-like receptor 7 and CTLA-4 polymorphisms and severe asthma was evaluated by calculating the odds ratio (OR) and 95% confidence interval(CI). The relationship between the genotypes of Toll-like receptor 7 and CTLA-4 polymorphisms and severe asthma were evaluated by logistic regression analysis. Results The proportion of TLR7 rs3853839 CC genotype, CTLA-4 rs231725 AA genotype, TLR7 rs3853839 C allele frequency and CTLA-4 rs231725 A allele frequency in severe asthma group and mild asthma group were higher than those in normal control group(P<0.05). The proportion of TLR7 rs3853839 CC genotype, the proportion of CTLA-4 rs231725 AA genotype, the frequency of TLR7 rs3853839 C allele, and the frequency of CTLA-4 rs231725 A allele in the severe asthma group were higher than those in the mild asthma group(P<0.05). TLR7 rs3853839 CC genotype (OR=10.32, 95%CI=5.59-23.89), CTLA-4 rs231725 AA genotype (OR=13.21, 95%CI=3.58-20.25), TLR7 rs3853839 C allele frequency (OR=11.32, 95% CI=4.25-21.14) and CTLA-4 rs231725 A allele frequency (OR=13.24, 95% CI=6.59-20.21) could increase the susceptibility to severe asthma(P<0.05). TLR7 rs3853839CC genotype, TLR7 rs3853839C allele frequency, CTLA-4 rs231725AA genotype and CTLA-4 rs231725A allele frequency were risk factors for severe asthma(P<0.05). Conclusion TLR7 rs3853839 CC genotype, TLR7 rs3853839 C allele frequency, CTLA-4 rs231725 AA genotype and CTLA-4 rs231725 A allele frequency are associated with the occurrence of severe asthma.