The position and normal accuracy of the automatic drilling in aircraft assembly will directly affect the quality of the final product. The process of automatic drilling is designed based on the aircraft’s digital model. However， in the assembly shop-floor， under the influence of superimposed multi-source assembly deviation， the physical shapes of large flexible structural parts like wing panels will inevitably deviate from the theoretical model. Therefore， the position and normal directions of connecting holes need to be corrected. In order to reduce the normal deviation and improve the drilling efficiency， we propose a normal correction technology based on interpolation of reference holes considering the structural characteristics of panel skins of large aircraft. The actual normal direction of each reference hole is calculated by the measurement values of laser displacement sensors， and the position deviations of the reference holes are obtained in conjunction with the visual measurement system. Based on the information of reference holes， the normal correction of the remaining holes is realized by using an interpolation algorithm. The test results show that the proposed correction technology can achieve normal accuracy within 0.3°， and the drilling efficiency can be improved by about 25% compared with the traditional correction technology.