刚去政府网站查了, 8岁以上就可以不用了.
Children may begin wearing a seatbelt once they are able to wear it properly (a lap belt flat across the hips, shoulder belt across the centre of the chest and over the shoulder), and if any one of the following criteria is met:
the child turns eight years old;
the child weighs 36 kg (80 lbs) or more; or,
the child is 145 cm (4 feet 9 inches) tall or taller.