Dielectric SiO2 has possible uses as an active layer for emerging memory due to its high on/off ratio and low operation voltage. However, SiO2-based memory that relies on the conducting filament still has limited endurance and stability. Here, we have constructed a passivated layer of SiO2 using Ag-doped SrTiO3, which serves as a Ag ion reservoir for the control of filament formation. It is demonstrated that the modified memristor presents an excellent endurance switching and could stably be operated in an ambient environment for 20 days without visible degradation. Based on the reliable switching, the synaptic functions such as excitatory postsynaptic current, paired-pulse facilitation, transition from short-term memory to long-term memory, and potentiation/depression have also been implemented. Furthermore, a 7 × 7 pixel array made from memristors has successfully mimicked simple learning and forgetting behavior. The experimental results offer an alternative approach for SiO2-based memristors and a possibility to be applied in neuromorphic computing.