The general form of differential tracker cannot properly deal with the problems of signal tracking phase lag, noise amplification, many parameters and complicated debugging when obtaining position information and velocity signals from a capacitive position sensor containing random disturbances. Based on the equivalent linear analysis of differential trackers, a composite form of differential tracker was proposed for position signal tracking and velocity signal estimation of position capacitive sensors. The simulations and experimental tests of MATLAB \\ SIMULINK show that the composite differential tracker can approach the original smoothly and the position signal and the velocity 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.