The invention discloses a ship sea-keeping test device, which is arranged on a ship model and used for testing seakeeping performance of the ship model. The ship sea-keeping test device comprises a horizontal cross bar, a vertical stand bar arranged vertically to the horizontal cross bar, a vertical sleeve sleeving the upper end of the vertical stand bar, stop plates arranged at the two ends of the horizontal cross bars, and two installation bases for supporting and mounting the horizontal cross bars. The bottom end of the vertical stand bar is fixedly connected to the upper surface in the middle of the horizontal cross bar; and the axial two ends of the horizontal cross bar pass through the installation bases and abut against the outer walls of the stop plates, and are fixedly connected through bolts respectively. The vertical sleeve sleeves the upper end of the vertical stand bar, so that when the ship model heaves, the vertical stand bar moves up and down; and when the ship model heaves, vertical displacement is not limited in the vertical direction, so that too much forced limit of the ship model is not needed, and accuracy of the displacement data, measured in the wave, of the ship model is high.