Self-assembly of cyclodextrin (CD) with guest polymers has attracted much attention owing to its biocompatibility and accessibility. In this study, we investigate the composition effect of poly(ethylene oxide)_m-b-poly(propylene oxide)_n-b-poly(ethylene oxide)_m (EO_mPO_nEO_m) triblock copolymers on lamellar or plate structures formed by complexation with β-CD. EO₅PO₂₉EO₅, EO₁₄PO₂₉EO₁₄, and EO₇₅PO₂₉EO₇₅ show periodic lamellar morphology consisting of single-crystalline pseudo-polyrotaxane (PPR) nanosheets with a thickness equal to the central PO length. This is because β-CDs selectively cover the PO component and cause the microphase separation between β-CD and EO layers. The thickness of the EO layers increases linearly with increasing number of EO units, which suggests that the EO chains are constrained into virtual cylinders with the diameter of the β-CD. This means that we can precisely control the thickness of both the crystal (β-CD and PO) and the amorphous (EO) layers in the lamellar structure. In contrast, EO₂PO₂₉EO₂ forms a thin plate structure, where not only PO but also EO chains are covered with β-CD. Furthermore, the length of the central PO component is necessary to form the lamellar structure with the phase separation between the β-CD and EO layers. These findings provide a more fundamental understanding to enhance the variety and applicability of CD-based self-assembled materials.