The invention discloses a building block pet assembling box which comprises a plurality of disassembling-type box units. At least one panel of each disassembling-type box unit is provided with a butt-joint window. The disassembling-type box units are spliced and assembled in any two or three of the X, Y and Z directions in a three-dimensional space. The disassembling-type box units form one or more pet walking channels through the butt-joint windows, wherein the pet walking channels are communicated with each other, and each pet walking channel is provided with at least one entrance and exit. The building block pet assembling box is simple in structure, small in space occupation and easy to assemble and disassemble, can be assembled into any shape freely, can adapt to different using spaces and using environments, and is not limited by the using environments. Due to the fact that the disassembling-type box units can be spliced and assembled in any two or three of the X, Y and Z directions in the three-dimensional space, space occupation is quite small, the complex and staggered pet walking channels can be formed, and the large enough playing space and the large enough living space can be provided for pets.