Formaldehyde (HCHO) is an important indicator of atmospheric reactivity and one of the main precursors of urban atmospheric aerosols, which controls the oxidation capacity in the troposphere. In addition, as a toxic gas, excessive HCHO will cause great harm to human health. Therefore, it is of great significance to realize the trace detection of HCHO. The research progress of trace detection of HCHO at home and abroad is reviewed, and the detection methods of HCHO, especially the spectroscopic detection methods, are introduced in detail from the detection principle, detection spectral line and the application of light source. In addition, several typical HCHO calibration devices are compared, and different trace HCHO detection technologies are analyzed and summarized from detection sensitivity, response, selectivity, cost, integration and so on. Finally, the applications of different detection technologies in field measurement are also introduced.