Repeat expansion diseases(REDs) are a group of genetic disorders caused by the pathological expansion of specific short tandem repeats(STRs) in genomic DNA. They are characterized by significant clinical and genetic heterogeneity. Owing to the complexity of their pathogenesis, effective treatments remain elusive. With the in-depth analysis of the pathogenesis of these diseases, along with the development and innovation of targeting tools in recent years, targeted therapy strategies have become a research hotspot, and some antisense oligonucleotide drugs have entered the clinical trial stage. This article aims to review the latest advances in basic research and clinical trial outcomes of targeted therapy at the DNA, RNA and protein levels. Currently, this field still faces key bottlenecks including a high risk of off-target effects, low delivery efficiency, and challenges in clinical translation. Future efforts should focus on the optimization and refinement of targeting tools and delivery vectors, as well as multilevel collaborative combination therapeutic strategies.Combined with precise clinical classification and staging, this will promote the fundamental transformation of REDs treatment from symptomatic supportive care to etiological intervention.