An analytical approach for the stiffness modeling of a novel towbarless aircraft tractor’s holding and lifting mechanism was presented. The movement of the holding and lifting mechanism was decomposed and particular interest was placed on the process that lifting the airplanes nosewheel after the backboards were closed. On the basis of the inverse position analyses, the compound limbs of the mechanism were analyzed by the static analysis and the corresponding deformations were calculated. The pose deformations of the carrying bucket caused by compound limbs were obtained by using the virtual mechanism method and according to the velocity mapping relationship between inputs and outputs．The total deformations of the mechanism were derived through the superposition principle at small strain．According to the relationships between the external load and the total deformation of the mechanism，the total static stiffness model of the mechanism was formulated. The stiffness distributes throughout the task workspace were evaluated and the model of the mechanism was validated by a commercial ANSYS software.