Over the last few years, CRISPR/Cas system has become a prominent tool in transcription regulation and genome editing. In addition, CRISPR/Cas system has shown remarkable potentials in developing novel biosensors for nucleic acid detection due to its unique capability for collateral cleavage of target nucleic acids and non-specific single stranded nucleic acids. The key to constructing highly sensitive CRISPR/Cas system-based biosensor usually relies on its combination with signal amplification strategies including nucleic acid amplification technologies or specific signal read-out methods. Thus, this paper aims to provide a comprehensive overview of CRISPR/Cas-based biosensors for nucleic acid detection by introducing different types of CRISPR/Cas system, highlighting the progress of signal amplification strategies used in CRISPR/Cas system-based biosensor along with nucleic acid amplification technologies (PCR, LAMP, RCA, RPA and EXPAR), sensitive signal transduction methods (electrochemical, and surface enhanced Raman spectroscopy), and special biosensing structure design. Current challenges and future prospective are discussed as well.