Manipulation in nano-scale is important to the development of Nano-technology, while position sensing is the base of nano-manipulation. Self-sensing is a method providing true sensor-actuator collocation and especially suitable for room-limited workspace. This paper introduced a self-sensing method for displacement measurement, based on charge amplifier. The principle of self-sensing was derived from piezoelectric constitutive equations, and a charge amplifier circuit was developed to obtain the displacement of piezoelectric stack. A series of experiments were conducted to evaluate the characteristics of our method. The results of the experiments and some characteristics of charge-amplifier based self-sensing method were presented.