This invention discloses a floating-point number operation circuit and a method thereof. The floating-point number operation circuit is configured to perform a fused multiplication and accumulation (fused mac) operation or a multiplication and accumulation (mac) operation on a first operand, a second operand, and a third operand, or perform a multiplication operation on the first operand and the second operand. The floating-point number operation circuit includes two rounding circuits, a multiplication circuit, a selection circuit, a control circuit, and an addition circuit. The control circuit controls the scheduling of various operations and the use of resources on each calculation path.