The removal efficiency and the relative removal efficiency between two different materials and three performance factors,normal removal rate,volume removal rate and sputtering yield,were analyzed in ion beam figuring process.With the Sigmund sputtering theory,the relation models between three factors and processing parameters,such as ion energy,ion flux and ion incident angle,were established.The experiments with samples of zerodur,SiO₂ and K4 glass were carried out to analyze these relations and to verify the theoretical models,which indicates that the removal efficiency increases with the ion current linearly and shows an approximate proportion to the square root of the ion energy.It also increases with incident angle and climbs the summit at about 60～80°.The relative removal efficiency is independent of ion flux,but has a little effect from beam energy,which can be ignored.However,the effect of angle on the relative removal efficiency is rather obvious.