The invention provides a phase step exciter and belongs to the technical field of stiffness tests. The phase step exciter is characterized by comprising a compression handle (1), a fixed shell (4), a clamping mechanism (5), an operating component (6), an energy storage spring (7), a linear bearing (8) and a baffle (10). The phase step exciter has the advantages that an overall system is simple in structure, so that the design cost is effectively reduced; the clamping mechanism and the operating handle are adopted by the phase step exciter, operation is easy and convenient, and common workers can complete relevant operation; a magnitude adjusting nut is installed on the phase step exciter, and step signals for inputting different magnitudes can be set; in this way, the drive mode is changed, the working principle of the phase step exciter is also changed, the structural type is changed, and the phase step exciter has the advantages of being convenient to carry, easy to operate, simple in structure and low in cost, causing low degree of population and the like.