The invention relates to a four-axis air cylinder. The four-axis air cylinder comprises a valve body, and four air cylinder assemblies arranged on the valve body in a cross shape. Each air cylinder assembly comprises a cylinder body arranged on the valve body, a cylinder cover arranged on the cylinder body, a piston movably arranged in the cylinder body, and a piston rod in linked cooperation withthe piston. Rodless cavities are formed between the pistons and the side wall of the valve body, rod cavities are formed between the pistons and the cylinder covers, a first ventilation interface anda second ventilation interface are formed in the valve body, first air ways communicating with the rodless cavities of the air cylinder assemblies are arranged on the valve body, second air ways stretching to the air cylinder assemblies are arranged on the valve body, and third air ways communicating to the positions between the second air ways and the rod cavities are arranged on the cylinder bodies of the air cylinder assemblies separately. The four-axis air cylinder has the beneficial effects of being simple in structure, stable and reliable in performance, convenient to operate, long in service life and low in cost.