As the aircraft's speed increases, the research on hypersonic aerodynamics, hypersonic combustion flow field, and aircraft aerodynamic characteristics has become more and more important. The conventional velocity measurement methods are increasingly limited in the complex hypersonic flow field, and new measurement techniques need to be investigated to meet the demand for the accurate measurements of the flow. Therefore, the molecular tagging velocimetry is becoming a hot research topic because of its advantages of non-intrusiveness and no limitation of following behaviors. This paper describes the basic principles, main parameters, and operating characteristics of nanosecond laser molecular tagging velocimetry and femtosecond laser molecular tagging velocimetry, analyzes the challenges faced by these techniques in measurement and discusses the prospects of their application in science and engineering fields. This paper provides a reference for the development of velocity measurement techniques in the hypersonic complex flow field.