The invention provides an engine cooling water jacket and an engine. The engine cooling water jacket comprises a water jacket body, and the water jacket body sleeves the outer circumference of one endof a cylinder sleeve of the engine so that a gap can be formed between the inner wall of the water jacket body and the outer wall of the cylinder sleeve to form an annular cooling water cavity. The engine cooling water jacket further includes a water inlet pipe disposed on one side of the water jacket body, the cooling water cavity communicates with the water inlet pipe, and cooling water can enter the cooling water cavity through the water inlet pipe to cool the cylinder sleeve. The cooling water jacket is a separate component independent of a machine body of the engine, a tappet cavity is integrally formed above the cooling water jacket, the casting processability of the machine body of the engine can be effectively improved, the structure of the machine body is simplified, and the height of the cooling water jacket is adjusted to control a cooling area of the cylinder sleeve.