Abstract: In order to study effects of micro-grinding parameters on flatness of optical fiber lens and reduce flatness error of optical fiber lens in micro-grinding, a group of orthogonal experiments of micro-grinding 30° oblique fiber lens on a single fiber with 125 μm diameter are carried out in this paper. Based on grinding forces model of micro-grinding and elastic beam deformation theory of material mechanics, effect rule of micro-grinding parameters on flatness of optical fiber lens is analyzed. Theoretical analysis and experimental results show that overhang length of optical fiber has the greatest influence on flatness of oblique optical fiber lens, while increasing overhang length of optical fiber will result in a larger flatness error of oblique optical fiber lens and appropriate micro-grinding parameters can obtain smaller flatness error of oblique optical fiber lens. Appropriate micro-grinding experiment results in 30° oblique fiber lens with flatness 3 μm.