To solve the problems of easy layering，slow dissolution of drag-reducing agents，and significant environmental pollution in the transportation process of conventional white oil-based slickwater systems，the drag reducing agent F4 was selected through measurement of the dissolution and viscosity-increasing properties drag reducing agents F1—F6 with different molecular weights and ionic degrees. By screening thickeners，dispersants，and solid-liquid ratios，a biodiesel-based suspension drag reducer was developed as follows：34.0% biodiesel+3.0% thickener 2#+3.0% dispersant 3#+60.0% drag reducer F4. A variable viscosity and slickwater fracturing fluid system was constructed by combining biodiesel-based suspension drag reducers with clean up additive and anti-expansion agents. The experimental evaluation results showed that drag reducer F4 had good thermal stability with an apparent viscosity retention rate of 33.0% after shearing at 180 ℃ for 2 hours at constant temperature. The variable viscosity and slickwater fracturing fluid had good shear and temperature resistances. The viscosity retention rate could reach over 90% at room temperature and over 50% at 90 ℃ after shearing at the shear rate of 170 s^-1. Among them，the viscosity retention rate of high-viscosity slickwater fracturing fluids could reach over 70%，and the drag reduction rate of low-viscosity slickwater fracturing fluids could reach over 70%. The sand-carrying performance of high-viscosity slickwater fracturing fluids was better than that of low and medium-viscosity fluids，and the minimum settling rate was 0.005272 m/min. The surface tension of the variable viscosity slickwater fracturing fluid after breaking was less than 27 mN/m，the interface tension was less than 2.0 mN/m，the viscosity of the fracturing fluid was less than 5.0 mPa s，and the residue content was less than 50 mg/L，meeting the standard requirements.