In order to investigate the factors affecting the hierarchically ordered structures of the rod–rod block copolymers, SmPn based on two polynorbornene-based mesogen-jacketed liquid crystalline (LC) polymers PNb12POSS having side-chain polyhedral oligomeric silsesquioxane (POSS) units and PNb10PP (with a side-chain calamitic mesogen) was designed and synthesized by ring-opening metathesis polymerization, in which S and P refer to the two segments PNb12POSS and PNb10PP, respectively, whereas m and n refer to the ratios of monomer to catalyst during polymerization of PNb12POSS and PNb10PP, respectively. Investigation on the phase structures and behaviors of SmPn samples indicates that the LC and crystalline structures of the two segments are similar to their homopolymers. The PNb10PP segment forms a smectic A (SmA) phase with the ordered packing of the rod-like mesogens, and the PNb12POSS segment forms a hexagonal columnar (Colh) phase with the crystal of POSS units. The volume fraction of PNb12POSS (f PNb12POSS) plays an important role on the microphase separation of SmPn. The asymmetry between the two blocks becomes more pronounced with increasing f PNb12POSS, resulting in a larger bending curvature, and the microphase-separated structure changes from lamellar (LAM) to hexagonally packed cylinders (HEX) for S10P30, S20P30, and S30P30. Moreover, the PNb12POSS segments in S20P30 and S30P30 form Colh phases that can be clearly observed by transmission electron microscopy. However, because of the slow kinetics of the polymer chains owing to the high molecular weight and rigidity, sample S30P120 having the lowest f PNb12POSS value cannot form ordered structures, while S80P120 only forms a HEX structure lacking regularity with a size of ∼40 nm.