According to the deformation characteristics of large truss structure, a 3d deformation measurement scheme combining digital image correlation method and laser ranging is proposed compared with the traditional detection principle based on four-quadrant detector, the new method has the advantages of high range, three-dimensional measurement and easy to arrange in complex environment.In order to meet the more complex requirements of the synthetic aperture radar (SAR) on the sky, we use the axis shifter camera as the measuring camera instead of the traditional one, which can ensure that a single camera can cover a measurement range of up to 50m, avoiding the problem of low accuracy caused by vibration and transmission error of multiple cameras.To further demonstrate the accuracy of DIC method, we adopted a series of translational platform experiments, which proved that the digital image correlation can still reach the accuracy of 0.05pixel when using the Angle reflector, which corresponds to the accuracy of less than 0.15mm beyond 50m.