Lead-free potassium sodium niobate ceramic thin films were synthesized using rf magnetron sputtering technology for MFIS structures. The optimal sputtering parameters of the as-deposited KNN thin films for depositing times of 1h were obtained. Regarding the measured physical properties, the micro-structure and thickness of as-deposited KNN thin films for different oxygen concentration were obtained and compared by XRD patterns and SEM images. The surface roughness of KNN thin film was also observed by AFM morphology. The average grain size and root mean square roughness were 250 and 7.04 nm, respectively. For KNN thin films in the MFIS structure, the capacitance and leakage current density were 280 pF and 10-8A/cm2, respectively. We investigated that the leakage current density and the memory window increased, the capacitance critically increased as the oxygen concentration increased from 0 to 40%. However, the excess oxygen concentration process was decreased the electrical and physical of as-deposited KNN thin film. The effect of oxygen concentration on the physical and electrical characteristics of KNN thin films was investigated and determined.