Display image compensation method and device and tiled display device

The invention provides a display image compensation method and device and a tiled display device (comprising a light-emitting diode display panel and a liquid crystal display panel), and the method comprises the steps: obtaining an initial gray-scale value and a corresponding initial optical value of the light-emitting diode display panel under a reference picture, and a target optical value of the liquid crystal display panel under the reference picture; the method comprises the steps of obtaining an initial gray-scale value, determining an initial optical difference value according to the initial gray-scale value, obtaining an iteration step length, determining a current gray-scale value according to the initial gray-scale value, the initial optical difference value and the iteration step length, and determining a reference target gray-scale value of the light-emitting diode display panel under a reference picture according to the difference between a transition optical value (determined according to the cu