Pakistan have lost all three group matches while defending champions marked their first victory of the event after two losses.
No goal was scored during the first quarter of the match. Australia scored first goal during second quarter of the match and posted two more goals in the fourth quarter.
Australian Jeremy Hayward slammed in two penalty corners and Jacob Whetton netted the third.
According to new rules of champions trophy all eight teams have advanced into the quarter-finals.
Pakistan will take on Netherlands in the knock-out stage.
