In order to realize a six-degree-of-freedom (six-DOF) piezoelectric energy harvester through integrating six single-degree-of-freedom (single-DOF) piezoelectric energy harvesters into a parallel mechanism, which has six sensitive axes and broader bandwidth, a single-DOF piezoelectric energy harvester utilizing a clamped beam configuration is proposed in this paper. It consists of a proof mass and a corrugated clamped beam covered by piezoelectric patches, where the proof mass is mounted at the center of the beam. Compared to the conventional energy harvester, the proposed single-DOF vibration energy harvester has two parallelism mounting planes at the support of the beam and the mass, separately, and can be easily integrated into the parallel mechanism. The stiffness equation of the single-DOF piezoelectric energy harvester is established and analyzed. On this basis, the natural frequency and stress distribution of the harvester are investigated through analytical developments and numerical simulations. These results show that the proposed single-DOF vibration energy harvester has output with the excitation along its axis, while no outputs with the excitation perpendicular to the axis, and the natural frequency and stress distribution can be accurate estimated by the established theoretical models.