Abstract: In this paper, the mesogen-jacketed liquid crystalline polymer PBPCS melt spinning process is simplified to explore the melt's shear behavior by the approximation approach. Firstly, the constitutive equation is established through the satellite coordinates, and then Dewitt model is derived. Moreover, the ARES shear rheology experiment show PBPCS melt is shear-thinning and its viscosity is structure-sticky. Dewitt theoretical model and ARES experiments both demonstrate that the shear rate should less than 120min^-1 to avoid melt frangible.