A handle height adjusting mechanism includes an upper fixing base, a lower fixing base pivoted to the upper fixing base, and an engaging component movably disposed between the upper fixing base and the lower fixing base and for engaging with the upper fixing base and the lower fixing base. The engaging component includes a protrusion. The handle height adjusting mechanism can adjust a handle height and prevent accidental folding operation of a child carrier for enhancing safety. The present application further discloses the child carrier having the handle height adjusting mechanism.