To eliminate the external precision displacement sensor, reduce the volume of the micro assembly and micro operation system, and reduce the system cost, the self-sensing method is used to obtain the output displacement of the piezoelectric actuator. Firstly, the deformation of the piezoelectric actuator under the action of voltage is utilized. Meanwhile, the piezoelectric actuator is be polarized and charges on the surface of its surface is generated. Adisplacement self-sensing method of the unbalanced current integral piezoelectric actuator is proposed. Secondly, considering the influence of the leakage current and dielectric absorption current of the piezoelectric actuator, as well as the bias current of the operational amplifier on the self-sensing accuracy, the self-sensing expression and the self-sensing parameter identification method which can accurately reflect the output displacement of the piezoelectric actuator are given. Finally, on the basis of identifying the self-sensingparameters of the piezoelectric actuator,experiments evaluate the effectiveness of the proposed precision displacement self-sensing method. The results show that the self-sensing displacement has a sub-micron resolution of 0.24 μm. In terms of static displacement self-sensing，the maximum relative error of self-sensing displacement is 1.17% in the displacement range of 0～118.9μm. In terms of dynamic displacement self-sensing， the maximum relative error of self-sensing displacement is 1.45% in the frequency range of 0~100 Hz. The proposed precision displacement self-sensing method cannot only realize the static long-time, but also achieve the dynamic fast high-precision and high-resolution displacement self-sensing.