The invention provides a SiO2/PVDF-HFP composite fiber membrane and a preparation method and application thereof. The preparation method comprises the following steps: preparing a PVDF-HFP nanofiber membrane: preparing a PVDF-HFP spinning precursor solution, and preparing the PVDF-HFP nanofiber membrane by utilizing an electrostatic spinning method; preparing a SiO2 fibrous membrane; respectivelypreparing a SiO2 precursor solution and a template polymer solution, mixing the two solutions to prepare a hybrid SiO2 spinning precursor solution, preparing a hybrid SiO2 nanofiber membrane by usingan electrostatic spinning method, and carrying out high-temperature annealing on the obtained hybrid SiO2 nanofiber membrane to remove the template polymer to obtain a SiO2 fiber membrane; and material compounding: bonding the PVDF-HFP nanofiber membrane and the SiO2 fiber membrane by using a special adhesive for the battery to obtain the SiO2/PVDF-HFP composite fiber membrane. The composite fibermembrane has high mechanical strength, high thermal stability, high porosity, high electrolyte absorption rate and high lithium ion conductivity, the performance of the battery can be improved when the composite fiber membrane is applied to the lithium battery, and when the lithium battery is at a high charge-discharge rate, the battery diaphragm can generate a hole closing effect, so that the safety of the battery can be improved.