Most crude oil produced in China is waxy crude oil. In engineering, polymer pour-point depressants (PPDs) are commonly added to improve the low-temperature rheology of waxy crude oil, thereby enhancing pipeline operational economy and safety. PPDs are chemically synthesized polymers or condensates whose molecular chains typically contain nonpolar long-chain alkyl groups capable of interacting with wax molecules and polar functional groups that influence wax crystal growth and dispersion. Among these, ethylene-vinyl acetate random copolymer (EVA) and polyacrylate comb-type polymers (PA) are two commonly used types of pour-point depressants for waxy crude oil. Increasing the microcrystalline wax content raises the pour point, gel point, and wax appearance temperature of waxy oil. At temperatures below 25℃, the viscosity of waxy oil initially increases and then decreases as the microcrystalline wax content rises. Due to its higher precipitation temperature, microcrystalline wax can serve as a crystallization nucleus for paraffin wax, altering the morphology of precipitated wax crystals. At low concentrations, microcrystalline wax transforms coarse acicular wax crystals into numerous fine acicular crystals, deteriorating rheological properties. At high concentrations, however, it promotes the formation of more dispersed cluster-shaped wax crystals, thereby modifying rheological behavior.