The Ta_2 O_5 thin films was made by ion-beam sputtering.In this work,the Ta_2 O_5 thin films were prepared on the K9 glass using the single ion-beam sputtering with a range of oxygen flux.As the oxygen flux increased,the rate of deposition decreased from 0.26 nm/s to 0.23nm/s.The refractive index was 2.075 in 1000nm at 30 sccm.The stress increased along with the increasing of oxygen flux.In the work,the compressive stress increased from 319.55 Mpa to 410.92 Mpa.