The invention discloses a water-cooled oil-free air compressor, and relates to the technical field of air compressors. According to the technical scheme, the water-cooled oil-free air compressor is characterized by comprising a box body, two air cylinders and a motor arranged in the box body, wherein the motor comprises a rotating shaft, cranks and fans are fixedly connected to the two ends of therotating shaft, the air cylinders comprise cylinder sleeves and cylinder covers, pistons are slidably arranged in the cylinder sleeves, the pistons and the cranks are connected through connecting rods, and air supply pipes are arranged between the two cylinder covers in a communicating mode; and the water-cooled oil-free air compressor further comprises a water-cooled pipe and a water pump used for driving liquid in the water-cooled pipe to flow, the water-cooled pipe comprises two heat dissipation parts which are correspondingly close to the end faces of the two fans and two heat absorbing parts which are correspondingly tightly attached to the two cylinder sleeves, and a closed loop is formed by the heat dissipation part and the heat absorbing part on one side of the box body of the water-cooled pipe and the heat dissipation part and the heat absorbing part on the other side of the box body of the water-cooled pipe. According to the water-cooled oil-free air compressor, heat dissipation is carried out on the air cylinders in a water-cooled mode, so that the working states of the air cylinders are improved, and the service life of the air compressor is long; and heat absorption sleeves are arranged, so that the heat dissipation effect of the air compressor is further enhanced.