The invention relates to a two-stage pressure-control overflow-preventing breather valve. An exhaust valve core is pressed on an exhaust valve seat by an exhaust valve spring; the bottom end of the exhaust valve seat is fixed with the top end of a float lever through a connecting rack; a floating bowl is movably matched with the float lever through a center hole of a top plate and a center hole of a base plate; floating bowl springs of which two ends are respectively supported against the top plate and the base plate are sleeved on the float lever in the floating bowl; the base plate of the floating bowl is a moving plate; an air flue is arranged at the upper end of the float lever and is used for communicating a top hole on the float lever with a side hole; and when the floating bowl rises along the floating lever, the side hole is positioned in the floating bowl. With the structure, the two-stage pressure-control overflow-preventing breather valve has the advantage of simple structure; and the breathing level and the safety level are improved and the overflow-preventing effect is also achieved.