As energy consumption continues to rise， and conventional resources cannot meet daily needs， deep well drilling is particularly important. However， problems such as increased viscosity of drilling fluid， deterioration of rheology caused by high temperature at the bottom of the well have made the high temperature resistant viscosity reducer one of the indispensable drilling fluid treatment agents. To reduce the viscosity of the drilling fluid and improve the rheology， viscosity reducers mainly disassemble or block the formation of the grid structure between clay particles. In reference to the relevant research literature， this paper summarizes the research status of domestic drilling fluid viscosity reducers in the past ten years with emphasis on three types of viscosity reducers： synthetic polymers， modified natural materials， and industrial waste-made viscosity reducers. In view of the current problems， it is pointed out that in the future， low-cost and environment-friendly viscosity reducers suitable for high-temperature， high-salt and high-density drilling fluids should be developed at the molecular structure design level. At the same time， it pays attention to the utilization of industrial waste and the speeding up of the technology transformation through field applications. In recent years， synthetic polymer viscosity reducers have been studied mostly and developed the fastest. This article focuses on the development status and prospects of this type of viscosity reducer.