Abstract: The present invention provides a resolution conversion method and device, and UHDTV. The resolution conversion method includes the following steps: acquiring a diagonal interpolation parameter matrix in the vertical direction and a diagonal interpolation parameter matrix in the horizontal direction; performing a diagonal interpolation processing to the input signal that the resolution thereof is to be conversed to acquire a target resolution signal on basis of the diagonal interpolation parameter matrix in the vertical direction and the diagonal interpolation parameter matrix in the horizontal direction. By performing a diagonal interpolation processing to the input signal that the resolution thereof is to be conversed according to the diagonal interpolation parameter matrix in the horizontal and vertical directions, on one hand, image distortion is reduced, and on the other hand, image blur and image aliasing can be effectively avoid, and clarity of the image is thus improved.