Objective To investigate whether there is a causal relationship between asthma and chronic obstructive pulmonary disease（COPD） using the two-sample Mendelian randomization（MR） approach. Methods Single nucleotide polymorphisms（SNPs） strongly associated with asthma were obtained as instrumental variables（IVs） from the pooled data of genome-wide association studies，and the inverse variance weighted（IVW） method was used as the main analytical method，assisted by the methods of MR-Egger，weighted median，simple model，and weighted model，to evaluate the causal relationship between asthma and the risk of COPD. At the same time，the MR-PRESSO test was used to detect whether there was an outlier SNP，and the MR-Egger intercept test and the Cochran Q test were used to evaluate the horizontal pleiotropy and heterogeneity of IVs. Results A total of 61 SNPs were included，and IVW results showed that asthma is a risk factor for COPD.（odds ratio［OR］=1.146，95%CI=1.023-1.283，P=0.020； OR=1.153，95% CI=1.003-1.326，P=0.045），and the results of the other four auxiliary analysis methods were consistent with the results of IVW. The results of the MR-PRESSO test，the Cochran Q test，the MR-Egger intercept test，and the leave-one-out method all showed the stability of the above results. Conclusion Asthma may increase the risk of COPD.