A harness for an animal, including a chest strap, an abdominal strap and a back strap; the chest strap is provided with a tightening member, the tightening member comprising a buckle, a tightening strap and a lead ring. The tightening strap passes through the buckle, two ends of the tightening strap are respectively connected to two sides of the chest strap, and the lead ring is connected to a middle of the tightening strap. The harness of the present invention can be effectively used to restrain an animal from rushing and relief the animal from excessive stress, and also to prevent an owner from being dragged by the animal.