The invention discloses an automatic stacking device of concrete blocks and a stacking process thereof. The device mainly comprises a layer board returner which separates the layer boards and the concrete blocks, a primary block stacking machine, a side stacking machine which transfers the concrete blocks to a on a rotary table, the rotary table which rotates the concrete blocks at 90 degrees, a secondary block stacking machine which transfers the concrete blocks from the rotary table to the inner side of a hydraulic clamp, a stacking platform which stacks the concrete blocks and a palletizing machine which recovers the layer boards. According to the invention, an industrial personal computer and a PLC (Programmable Logic Controller) are used as a core of a control system, and an industrial camera and the Ethernet are used for site and remote monitoring, so that high automation of the concrete block stacking process is realized. The device is of strong adaptability to different types of concrete blocks and production sites, and the labor intensity of workers is remarkably reduced, and the efficiency and quality of concrete block production are improved.