Improved understanding of the impact of crystal mush rheology on the response of magma chambers to magmatic events is critical for better understanding crustal igneous systems with abundant crystals. In this study, we extend an earlier model by (Liao et al, 2018) which considers the mechanical response of a magma chamber with poroelastic crystal mush, by including poroviscoelastic rheology of crystal mush. We find that the coexistence of the two mechanisms of poroelastic diffusion and viscoelastic relaxation causes the magma chamber to react to a magma injection event with more complex time-dependent behaviors. Specifically, we find that the system’s short-term evolution is dominated by the poroelastic diffusion process, while its long-term evolution is dominated by the viscoelastic relaxation process. We identify two post-injection timescales that represent these two stages and examine their relation to the material properties of the system. We find that better constraints on the poroelastic diffusion time are more important for the potential interpretation of surface deformation using the model. We also find that the combination of the two mechanisms causes magma transport to reverse direction in the system, which would successively expose crystals to magma with different chemical compositions.