A quartz tuning fork is a kind of piezoelectric resonators. Quartz tuning forks can be modified as sensors to measure various properties, such as force, acceleration, displacement, and many other ones. A method to extend the measurable range of a quartz tuning fork based displacement sensor is devised in this paper. The experimental results demonstrate that the linear measurable range of the proposed displacement sensor is 100贡m, and the resolution is 300nm.