Abstract: Biofilm is widely used in the biological treatment of industrial wastewater and domestic sewage.As a research method, microelectrode technology has become an important means to study the mass transfer and degradation of materials in biofilms due to its high measurement accuracy and fast response time.In this paper, the classification and characteristics of microelectrode, the establishment of measurement microreactor and the role of microelectrode technology of biofilm in recent years were described. The use of microelectrodes to directly measure the change of indicators is the basis. The analysis of the measured data is the key to understand the biofilm. The combined application of microelectrode technology and other technologies is the trend of the future microelectrode technology.