In this paper, a dual-mode piezoelectric stick-slip actuator is proposed. The combination of a non-resonant mode and a resonant mode is realized by an intermediately fixed piezoelectric unimorph and a flexible amplifying mechanism, so that the actuator can achieve high motion accuracy and fast response. The appropriate flexible amplification mechanism parameters are obtained by the finite element method, and the feasibility of the dual-mode operation of the driver is analyzed and verified. The dynamic model of the actuator is established, and the test system is set up. The experimental results show that the stick-slip actuator driven by an intermediately fixed piezoelectric unimorph can achieve dual-mode operation. In non-resonant mode, the prototype can achieve a minimum step of 0.056 μm and a maximum output load of 1.2 N. In resonant mode, the maximum output speed of the prototype is 12.56 mm/s and the maximum output load is 1.4 N.