Shear deformation during plastic mechanical recycling process related to the degradation of mechanical properties in recycled plastic products. From our previous work, it can be found that the physical degradation affects to the changes of morphology and structure of semi-crystalline plastics. In this study, the detailed investigation of the changes of crystalline lamellar and amorphous phases of low-density polyethylene (LDPE) during shear deformation will be examined by the combination of rheometer and Raman spectroscopy; rheo-Raman spectrometer. The recrystallization after shear treatment will be also investigated and compared with the original LDPE without shear treatment. This study is expected to explain the changes of LDPE structure at before, during, and after shear deformation and the relationship with viscoelasticity and mechanical properties of shear deformed product in order to develop the quality of mechanical recycling process.