Abstract: Study on tolerances of diameters of mounting holes and distances between them is very important for installation of aircraft equipment.Also,it is of great economical significance in shortening the final assembly cycle of aircraft production and the assembly cycles for sections,panels or modules,and in reducing man-hours and tooling cost,while ensuring the aircraft design accuracy and interchangeability.The problems discussed in this paper are as follows:1.The dimensional tolerances of diameters of mounting holes and distances between them for aircraft equipment are investigated on the basis of Kalman filtering theory.The accuracy obtained is higher than that achieved with current statistical methods,and it is the most valuable that unmea-surable dimensions can be estimated by measurable ones;2.Optimum estimation of manufacturing accuracy achievable with current state of arts is provided;3.A new theoretical basis for establishment of error bands is proposed.