The disclosure relates to the field of displaying a projected picture, and particularly to a projection device, and a method for adjusting a projected picture. In an embodiment of the disclosure, the method includes: acquiring an image of a physical screen through a camera, and determining a projection of the physical screen onto a vision plane of the camera; determining rotation parameters and translation parameters of the projection device according to the vision plane and the projection of the physical screen; and adjusting the projection device according to the rotation parameters and the translation parameters of the projection device.