The invention relates to the field of a large-screen display device, in particular to a device for eliminating a joint seam of a rear projector splicing wall. The rear projector splicing wall comprises a plurality of splicing wall units, wherein a joint seam is respectively formed between every two adjacent splicing wall units, the joint seam is provided with a light emitting diode (LED) lamp and an LED lamp display control device, and the LED lamp is connected with the LED lamp display control device. The joint seam of the rear projector splicing wall is provided with the LED lamp, so that the light transmitted from the LED lamp passes through the joint seam to be displayed, the problem of the black edge of the joint seam of the rear projector splicing wall can be effectively solved, the all-day display effect of the splicing wall can be greatly improved, and the display effect is remarkable; and moreover, the LED lamp display control device reads pixels on the edges of the splicing wall units, and the pixels on the edges read are displayed by controlling the LED lamp, so that the image display continuity is good, and the phenomenon that the image is split suddenly can be avoided.