 Abstract solid composite electrolytes, SEs, combine the advantages of solid polymer electrolytes, SPs, and inorganic ceramic electrolytes, ISIS, but face challenges such as low ionic conductivity, poor interfacial stability, and high interfacial resistance. This work presents advances in SEs applied in all solid state lithium batteries, including the ion migration mechanism, strategies to enhance ionic conductivity, and construction methods of low resistance and stable interfaces with both cathode and anode. Feature development directions include enhancing ionic conductivity by developing novel SPs with special morphology of ISIS for advanced all solid state lithium batteries. This article was authored by Song Li, Shouqi Zhang, Liu Shen, and others.