CRISPR activation (CRISPRa) is a CRISPR tool that provides a powerful way to activate genes on a large scale in a focused manner. CRISPRa takes full advantage of a modified version of dCas9, a Cas9 mutation that does not have endonuclease activity, and fused with transcriptional activators. The screening of CRISPR-based transcriptional activation has been used to research mechanisms of human diseases, screen drug targets, and establish causal relationships between gene expression and cell fate determination. In addition, CRISPR-based gene activation is expected to be used to target endogenous gene regulatory elements to increase the expression level of normal gene copies to correct diseases caused by haploid function.