The invention discloses a single-column type offshore power generation device. The single-column type offshore power generation device comprises a foundation block, wherein sliding plates are fixedlyconnected to the left side and the right side of the top of the foundation block, sliding sleeves are movably connected to the surfaces of the sliding plates, the two sliding sleeves are fixedly connected through a fixing plate, a threaded rod is fixedly connected to the middle point of the top of the fixing plate, and the tops of the two sliding plates are fixedly connected through a placing plate. According to the single-column type offshore power generation device, the sliding plates, the sliding sleeves, the fixing plate, the threaded rod, the placing plate, a connecting base, a sliding block, balls, a fastening bolt, a threaded sleeve, a rotating handle and a fixing sleeve are arranged to be matched with a supporting column, so that the height of the single-column type marine power generation device can be adjusted, the height can be adjusted in time according to the water level of the seawater, the obstruction of the water level to a fan blade is avoided, and therefore normal operation of the single-column type offshore wind power generation is guaranteed.