A novel experimental technique to follow the crystallization processes of poly(propylene)/MWCNT composites that experience a steady shear deformation using dynamic melt rheometry is described. The effects of heterogeneous nucleation, temperature, and preshear on the crystallization behaviors were determined. A quantitative evaluation of crystallization kinetics difference between quiescent and preshear conditions could be achieved. By combining rheology with POM, we demonstrate that two different crystallization processes account for the shear‐enhanced crystallization at low and high temperatures, respectively.