The invention relates to a method and a kit for detecting Duchenne muscular dystrophy gene defects, and a primer composition. For the Duchenne muscular dystrophy gene defects, a pre-embryo implantation genetic detection method which is strong in universality, high in diagnosis rate and low in cost is established in a second-generation sequencing platform. According to the method, multiple PCR is carried out on a detected sample for a coding region locus and a target SNP locus of a Duchenne muscular dystrophy gene, and a library is built; then a multiplex PCR product is subjected to high-throughput sequencing analysis, and a haplotype of a mutant allele is constructed by combining with family information, so that a genotype of an embryo is judged; and finally a Duchenne muscular dystrophy gene defect detection result of an offspring is determined. According to the scheme, a cell level pre-experiment is omitted; and based on a high-throughput sequencing technology, different label sequences can be added to samples, so that a large number of samples can be analyzed at one time, and the average sequencing depth can reach more than 100X.