Volumetric fracturing is the main stimulation process for unconventional oil and gas production. Because of high pump speed，large fluid volume and large displacement，the fracturing fluids are required to possess the properties of continuous mixing， low friction and high flowback rate. Therefore，the "slickwater" fracturing fluid system is demanded. The core component of slickwater is polymer drag reducer，which directly determines the performance of slickwater. In this paper，the recent progress in the field of drag reduction in terms of drag reducer properties，drag reduction mechanism，effecting factors of drag reduction performances，were reviewed. The application situation of drag reducer in slickwater hydrofracking for unconventional oil and gas production were introduced. Finally，the future trends in developing polymer drag reducers were outlooked.