Alternative splicing is the key to human gene expression regulation and plays a decisive role in enlarging the diversity of functional proteins. Alternative splicing is an important biomarker in tumor progression, which is closely related to the development of tumors. Tumor cells tend to produce alternative spliceosome that are conducive to their progression. Therefore, targeting regulation of tumor-specific alternative spliceosomes is a potential strategy for tumor therapy. Herein, we provide a brief review of the complex relationship between alternative splicing and tumors. Alternative splicing works by removing non-coding sequences of pre-mRNA and assembling protein-coding fragments in different combinations, ultimately producing proteins with different or even opposite functions. Alternative splicing events can promote the transformation of tumor cells through apoptosis, invasion, metastasis, angiogenesis, and metabolism; they can also influence the effectiveness of cancer immunotherapy by affecting genes that play a key role in the immune pathway. We proposed that direct or indirect targeting of alternative splicing factors and oligonucleotide-based therapies are the main strategies to reverse tumor alternative splicing events. These findings will help us to better understand tumor-related alternative splicing and to develop new strategies for tumor treatment.