A one-way power conversion device (24) and a power system having the one-way power conversion device are provided. The one-way power conversion device (24) includes a one-way gearbox (18), a first transmission shaft (15), a second transmission shaft (16), and a swing rotation component (19). The device includes a combination of one or more one-way power conversion devices (24), which can absorb swinging powers coming from different directions and convert the swinging powers into an available one-way rotation power. The device can absorb the swinging power in any direction, and has the advantages of a high absorption and conversion efficiency, a stable power output, low costs of construction and maintenance, a high stability, and a wide application range.