All solid-state lithium ion batteries (ASSLBs) have attracted wide attention due to their safety and higher energy density than liquid lithium battery. Nevertheless, solid-state electrolytes (SSEs) increase the impedance of ASSLBs because of their low ionic conductivity and lithium-ion transference number (t(Li+)), resulting in the poor electrochemical performance of ASSLBs. We report a novel multimixing composite solid electrolyte (CSE) consisting of Li6.7La3Zr1.7Ta0.3O12 (LLZTO), PEO, PVDF-HFP, and LiTFSI. The CSEs with 10 wt % of LLZTO exhibit optimal performance, possessing a high ionic conductivity of 1.05 X 10(-4) S cm(-1) at 35 degrees C, an electrochemical stability window of 5.2 V, and a high t(Li+ )of 0.52 at 60 degrees C. ASSLBs with PEO/PVDF-HFP/LLZTO-10 wt %/LiTFSI (PPHT) electrolytes also show great rate and cycle performance at 60 degrees C. The initial discharge capacity of ASSLBs containing PPHT film is 133.4 mA h g(-1) at the current density of 0.5 C, and the capacity can remain at 132.6 mA h g(-1 )after 200 cycles. This work provides a multiblending CSE film that has implications for promoting the practical application of ASSLBs.