Using a pressuring and shearing device (PSD), we explored the simultaneous effects of pressure and flow on beta-crystal formation. Interestingly, pressure plays a versatile role in beta-crystal formation in isotactic polypropylene (iPP) mixed with beta-nucleating agent (beta-NA) when a flow field exists simultaneously. At a low pressure (5 MPa), amass of beta-crystals can be obtained Over the entire range of applied shear rates (0.0-24.0 s(-1)). As the pressure increases (50-100 MPa), a weak shear flow,(3.2 s(-1)) can profoundly suppress the beta-crystal formation. When elevating the pressure to 150 MPa, beta-crystals cannot be generated. The pressure and flow window to produce beta-crystals in iPP mixed with beta-NA were successfully summarized for the first time. The diversified beta-crystal formation-behaviors in iPP mixed with-beta-NA under the simultaneous effects of pressure and, sheaf-now-were well elucidated-by combining classical nucleation theory and the growth of different crystalline phases. Our current work lays a solid foundation to tailor beta-crystals in iPP mixed with beta-NA in practical processing and thus to optimize the mechanical properties of iPP products.