Abstract: When calculating retracting or lowering aerodynamic load of a landing gear, to give accurate aerodynamic coefficients of its componets is a key problem. In order to find the aerodynamic coefficients of main componets of a landing gear, we have carried out experimental study in FL-13 tunnel. Basing on the tunnel test, this paper discusses factors that should be considered when determining aerodynamic coefficients of main componets of a landing gear, and clarifies applied limits of data that are given by some references. This paper, thus, provides information to calculate retracting or lowering aerodynamic loads of a landing gear.