As the largest rocky layer in the Earth, the lower mantle plays a critical role in controlling convective patterns in our planet. Current mineralogical models suggest that the lower mantle is dominated by (Mg,Fe)SiO3 perovskite (SiPv; about 70 – 90% in volume fraction) and (Mg,Fe)O ferropericlase (Fp). Knowledge of rheological properties and textures of the major constituent minerals is critical in understanding dynamic processes of the deep Earth, and relating seismic observations to mineralogy. While individual properties of these phases have been studied, fewer informations on polyphase aggregates are available. Fundamental understanding about the stress-strain interactions among the phases and their effect on the bulk rheology still remains to be properly addressed. Here we examine stress/strain partitioning and rheological properties of two-phases polycrystals of CaGeO3 perovskite (GePv) and MgO, using Elasto-Visco Plastic Self-Consistent modeling (EVPSC). The models are based on deformation experiments at high pressures and temperatures, with in-situ measurements using synchrotron X-ray diffraction. We explore the applicability of these models for understanding yielding, rheological and textures properties of these polycrystals. We also discuss stress distributions between the two phases, relationships with active slip systems, and finally the implications for rheological and seismic properties of the lower mantle.