Mesoporous materials, due to its potential for advanced applications in catalysis and nanoscience, have attracted much attention in the past decade. In this work, mesoporous lithium aluminate (next called MLA) nanosheets with high specific surface area were prepared by a hydrothermal method using hex-adecyltrimethyl ammonium bromide (CTAB) as the template. A novel PEO-based composite polymer electrolyte has been developed by using MLA powders as the filler. The electrochemical impedance showed that the conductivity was improved simultaneously. A high conductivity of 2.24×10−5 Scm−1 at 25°C was obtained. The lithium polymer battery using this novel composite polymer electrolyte and with lithium metal and LiFePO4 employed as anode and cathode, respectively, showed high discharge capacity (more than 140mAhg−1 at 60°C) and excellent cycling stability as revealed by galvanostastically charge/discharge cycling tests. The excellent electrochemical performances at low temperature of the cells were obtained, which was attributed to the high surface area and channels structure of the filler. The excellent properties of the solid-state lithium battery suggested that, PEO16–LiClO4–MLA composite polymer electrolyte can be used as a candidate material for lithium polymer batteries.