In this paper, a new non-resonant, free motion based electromagnetic energy harvester is proposed for harvesting energy from low-frequency vibration sources. In this design, steel frame is beneficially utilized to enhance the flux and consequently the power density of the harvester. The steel frame can also function as a magnetic shield to protect the harvester from external magnetic field interferences. Prototype of this harvester is constructed and characterized experimentally. A dedicated model and simulation method including non-linear contact characteristics is presented in this paper for predicting the dynamic response of this harvester at different vibration frequencies and amplitudes, and different operation modes are characterized. The measured results have well validated the behaviors predicted by the proposed model. In particular, the developed prototype of this harvester can generate a power density 748 μW/cm 3 at a low-frequency of 4.5 Hz and 40 mm vibration amplitude. Compared to recently reported low-frequency energy harvesters summarized in Table 3, this new harvester has the superiority of high-power density. It is a non-resonant harvester so it can harvest energy for a wide frequency band.