In order to improve the thermal and mechanical properties of polylactic acid （PLA） electrostatic spinning fiber membrane， PLA/SiO₂ composite fiber membrane was prepared by sol-gel method and electrostatic spinning process， which was based from PLA as matrix and ethyl orthosilicate as silica precursor. The results showed that SiO₂ was successfully introduced into the PLA matrix， and the fiber membranes were prepared by electrostatic spinning. PLA composites prepared were amorphous and SiO₂ increased the molecular spacing of PLA. The introduction of SiO₂ could greatly increase the residual amount at 800 ℃. SiO₂ could improve the tensile strength and elongation at break of the fiber membrane composites. As 1% of ω（SiO₂） is added， the tensile strength and elongation at break increased to 2.82 MPa and 42.2%， respectively. The fibers in the electrostatic spinning fiber films were disordered， and the fiber thickness was not uniform. The holes of PLA were more obvious and dense when SiO₂ was introduced. In conclusion， when SiO₂ was introduced into PLA matrix， the residual amount at 800 ℃，the tensile strength and the elongation rate at break were significantly improved， and a compact pore structure was formed.