Solid polymer electrolytes (SPEs) hold great application potential for solid-state lithium metal battery because of the excellent interfacial contact and processibility, but being hampered by the poor room-temperature conductivity (~ 10⁻⁷ S·cm⁻¹) and low lithium-ion transference number ( $t_{{\mathrm{L}\mathrm{i}}^{+}}$). Here, a lamellar composite solid electrolyte (Vr-NH₂@polyvinylidene fluoride (PVDF) LCSE) with β-conformation PVDF is fabricated by confining PVDF in the interlayer channel of –NH₂ modified vermiculite lamellar framework. We demonstrate that the conformation of PVDF can be manipulated by the nanoconfinement effect and the interaction from channel wall. The presence of –NH₂ groups could induce the formation of β-conformation PVDF through electrostatic interaction, which serves as continuous and rapid lithium-ion transfer pathway. As a result, a high room-temperature ionic conductivity of 1.77 × 10⁻⁴ S·cm⁻¹ is achieved, 1–2 orders of magnitude higher than most SPEs. Furthermore, Vr-NH₂@PVDF LCSE shows a high $t_{{\mathrm{L}\mathrm{i}}^{+}}$ of 0.68 because of the high dielectric constant, ~ 3 times of that of PVDF SPE, and surpassing most of reported SPEs. The LiNi_0.8Co_0.1Mn_0.1O₂||Li cell assembled by Vr-NH₂@PVDF LCSE obtains a discharge specific capacity of 137.1 mAh·g⁻¹ after 150 cycles with a capacity retention rate of 93% at 1 C and 25 °C. This study may pave a new avenue for high-performance SPEs.