A flow rate control device consists of valve body with the first fluid path and the second fluid path, throttle hole being able to rotate in valve body for throttling refrigerant flow, porous transmission material used to form throttle component with throttle hole and used to rectify refrigerant passed through said throttle hole, throttling path enabling to switch fluid in two said paths on valve body to pass throttle component by turning throttle hole and open path enabling to let fluid in two said paths on valve body pass through valve body directly without passing through said throttle component.