A depth information processing device includes a first image capturing device, a second image capturing device, and a processor. The first image capturing device captures a reference image, and the second image capturing device captures a target image. The processor is coupled to the first image capturing device and the second image capturing device. The processor selects a reference block from the reference image, selects a plurality of target blocks corresponding to the reference block from the target image with different sample periods, and generates the depth information according to the reference block and a selected target block of the plurality of target blocks.