Developing solid electrolyte for alkali metal batteries is of important significance. A gel polymer electrolyte (GPE) based on the porous composite polymer membrane formed by blending of PEO, PMMA and P(VDF-HFP) is prepared, and the effects of the addition of nano-sized oxide fillers (Al2O3, TiO2, SiO2) on the characteristics of the composite GPEs are investigated. The composite GPE with filling of SiO2 has more amorphous region and porous structure which can hold more liquid electrolyte without leakage, so the composite GPE can provide high ionic conductivity at room temperature and large Li+ or Na+ transport number. Furthermore, the composite GPE possesses a large electrochemical window, superior thermal stability and excellent interfacial stability. The composite GPEs can be applied in a variety of lithium and sodium metal batteries and exhibit superior cycling stability and rate performance.