Aiming at obtaining position information and velocity signals from a capacitive position sensor containing random disturbances, the general form of differential tracker cannot well take into account the problems of signal tracking phase lag and noise amplification, many parameters and complicated debugging.Based on the equivalent linear analysis of the differential tracker, a composite form of differential tracker was applied to position signal tracking and velocity signal estimation of the position capacitive sensor. The simulations and experimental platform tests of MATLAB \ SIMULINK showed that the composite differential tracker can approach the original smoothly. The position signal and the speed signal can be effectively extracted. Compared with the general form differential tracker, the tracking signal phase lag and the speed signal noise can be better taken into account.