The emerging CRISPR/Cas9 gene editing technology can realize the manipulation of genes at the molecular level. It has the advantages of simple design, easy operation, good specificity and high efficiency. It is widely used in the study of potential mechanisms of tumorigenesis, development and metastasis and clinical treatment. Recent researches into the use of CRISPR/Cas9 for tumor therapy in vivo have focused on developing vectors. Non-viral nano-carriers developed by nanotechnology can efficiently deliver the CRISPR/Cas9 system into the body, providing a new way for the clinical application of CRISPR/Cas9 technology. In this review, we discuss the principle of CRISPR/Cas9, the current delivery forms of CRISPR/Cas9 and commonly used nano-delivery vectors. We highlight several nano-carriers including inorganic nanoparticles, polymer-based nanoparticles, lipid-based nanoparticles and others. We also summarize the characteristics, editing efficiency, applications and new studies of different nano-carriers. The applications and progresses of CRISPR/Cas9 in treating different tumors are also discussed.