A traceable method for potential use in calibrating the micro-force of nanoindentation instrument using a laser interferometer is proposed. The calibration system consists of a laser interferometer and a cantilever. The cantilever is used as force-sensing element, and the interferometer is used to measure the deformation of the cantilever caused by the force. When a force is applied to the free end of the cantilever, the cantilever is elastically deformed. If the system is calibrated for the relationship between the force and the resulting displacement, it can be used to measure the loading force of a nanoindentation instrument by measuring the displacement of the measurement point on the cantilever. The system calibration can be performed using a set of calibrated masses. The design, calibration and application of the force calibration system are introduced. The experiment results of measuring the forces of a nanoindentation instrument ranging from 10μN to 1mN using this method are given. Preliminary experiments and analysis show that the proposed method can be used to measure the micro-force of nanoindentation instrument. By use of this method, the measurement of the micro-force in nanoindentation instrument can be traced to SI units.