The invention relates to a three-dimensional video coding method and a three-dimensional video coding device. The three-dimensional video coding method comprises the steps of: acquiring a virtual drawing block obtained through virtual drawing by a B video block and a corresponding coded or uncoded A video block, or a virtual viewpoint image block corresponding to the B video block, and regarding the virtual drawing block or the virtual viewpoint image block as a
reference block; coding the B video block in a current coding mode to obtain a
precoding B video block, and acquiring a reconstructed virtual drawing block obtained through virtual drawing by the
precoding B video block and the corresponding coded or uncoded A video block; calculating space domain distortions and
time domain distortions of the
reference block and the reconstructed virtual drawing block, merging the space domain distortions and the
time domain distortions to obtain a drawing
distortion; loading a Lagrangian multiplier of a B video frame to obtain a
precoding bit number of the B video block, and calculating a rate-
distortion cost according to the drawing
distortion, the Lagrangian multiplier and the precoding bit number; traversing codes of all coding
modes, regarding the coding mode with the minimal rate-distortion cost as the optimal coding mode of the B video block; and acquiring a code of a next B video block until coding of the B video frames to be coded is completed. Therefore, the three-dimensional video coding efficiency is improved.