This study establishes the relationship between homogeneity of tetragonal zirconia polycrystalline (TZP) feedstocks and the kneading time in order to understand the kneading energy adsorption during the de-agglomeration period of pre-existing ceramic granules. Two spray-dried Y-TZP powders with different compress strengths were investigated using torque rheometer and transmission optical microscopy. Several properties, kneading torque (T), Casson viscosity (mu), Reynolds number (Re), and dispersive index (D-s) of the feedstocks were introduced, and monitored as a function of kneading time. Optimal processing windows were identified from the dependence of dispersive index with a power number (N-p). The best shear-kneading procedure was proposed in consideration of best feedstock homogeneity and shortest kneading time. One homogenous feedstock and two comparable cases were prepared for subsequent injection molding, debinding, sintering, and mechanical testing. The fracture strength of sintering parts by a partially homogeneous feedstock can be improved from 520 to 680 MPa by a homogeneous feedstock.