Normal stress differences behavior of polymeric particle suspension in shear flow is investigated. The first normal stress difference (N-1) in shear flow is found to mainly arise from the polymer matrix with a relaxation behavior altered by the presence of particles, which has its origin from the polymer chains trapped in the near-contact asymmetric regions of closely packed particles, while the second normal stress difference (N-2) is dominated by the microstructure of particles at high volume fractions. It is proposed that the stress tensor in a polymeric suspension is the sum of a particle-contributed stress arising from the microstructure interaction and a polymeric matrix contributed stress with a relaxation spectrum altered by the particle microstructure. A simple model is proposed to describe how the relaxation behavior of a polymer matrix can be changed by the confinements of particles in suspension. (C) 2014 The Society of Rheology.