An on-line linearity calibration platform for capacitive displacement sensors is proposed to implement the high-precision adjustment and the measurement of displacement. The symmetry axis for movement, the measuring axis of an interferometer and the measuring axis of a sensor are collinear in the platform, so that the Abbe error is decreased in principle. For the z/tip/tilt adjustment function in the platform, the alignment between the sensor and the target surface is realized. The composition and principle of the calibration method are introduced and the micro-displacement is adjusted by a symmetrical parallelogram mechanism. Then, the output compliance and stroke of the guiding mechanism are analyzed based on Compliance Matrix Method(CMM). The experiment result demonstrates that the stroke of the calibration platform is 735.162 μm and the errors are 7.410% and 4.633% comparing with that of the Finite Element Method(FEM) and CMM, respectively, which meet the requirement of the stroke. Moreover, the sensor linearity is improved from 0.014 21% to 0.006 231% after calibration calculation. The linearity calibration method has high-precision and it satisfies the requirement of fine displacement adjustment of the mechanism.