The invention discloses an internal combustion engine and a cylinder and a cooling water channel of the internal combustion engine. The cooling water channel comprises a body arranged around cylinder holes of the cylinder. A plurality of water channel cavities corresponding to the cylinder holes are formed in the two sides of the body. A first bolt hole and a first connecting hole are formed in the circular bead positions, between every two adjacent cylinder holes, of the body. The water channel cavities are communicated through the first connecting holes to form the water channel. The first bolt holes are arranged above the first connecting holes. First reinforcing ribs extending inwards and outwards are arranged between the first bolt holes and the first connecting holes. The inner sides and the outer sides of the first reinforcing ribs are connected with the body. In this way, the stress of bolts in the first bolt holes can be inwards and outwards transferred to the body through the first reinforcing ribs, and therefore stress concentration is avoided. Furthermore, the positions of the first connecting holes can approach the centers of the cylinder holes, so that the volume of the water channel is enlarged. Besides, after the positions of the first connecting holes approach the centers of the cylinder holes, under the condition that the cross sectional area of the water channel is not changed, it can be guaranteed that the horizontal size of the water channel is decreased, and production cost is reduced.