Lever-arm effect and flexure are the major error factors for transfer alignment of carrier aircraft's INS which affect the speed and accuracy of transfer alignment. The conditional compensation method of lever-arm effect is directly compensated according to the value which is gotten from calculation with the angular velocity and angular acceleration with lever-arm length under thinking the lever-arm length is fixed. Because of the influence of wave and so on, the flexure will be caused and the lever-arm length will change with the flexure. The new model of lever-arm effect with flexure was built according to analysis variability of lever-arm length with flexure, with the simulation, the relationship between the flexure and lever-arm acceleration is given and rationality of model is validated.