The invention provides a device for adjusting a sail angle. The device for adjusting the sail angle comprises a sail, a first base, a swing mechanism and a hydraulic rod, the sail is connected to the first base, the two ends of the hydraulic rod are respectively connected with the sail and the first base, the swing mechanism comprises a first gear device, a drive shaft and a second gear device, the first base is connected with the first gear device, and the first gear device and the second gear device are connected through the drive shaft. The device for adjusting the sail angle is simple in structure, can make the sail angle of a ship change more flexibly, so that the propulsion power of the sail to the ship is improved. A method for adjusting the sailing angle comprises the steps that the second gear device transmits power to the first gear device through the drive shaft, and the first gear device drives the first base to rotate, so that the sail achieves rotation of 360 degrees in the vertical direction. The sailing is driven by the hydraulic rod to complete tilt of 0-90 degrees, the method can complete adjusting of the sail angle of the ship, and the process is simple.