A child carrier , characterized in that the child carrier comprises: a booster seat ; and a leg assembly detachably installed on the booster seat , the leg assembly comprising: at least one upper support detachably installed on the booster seat ; and at least one lower support detachably installed on the at least one upper support ; wherein the child carrier is in a high chair mode when the at least one lower support and the at least one upper support are respectively installed on the at least one upper support and the booster seat to connect the leg assembly to the booster seat , the child carrier is in a youth chair mode when the at least one upper support is installed on the booster seat and the at least one lower support is detached from the at least one upper support , and the child carrier is in a booster mode when the at least one upper support is detached from the booster seat to separate the leg assembly from the booster seat , wherein the child carrier further comprises a seatback detachably installed on the booster seat ; wherein the seatback is rotatable relative to the booster seat ; and wherein the seatback comprises at least one pivoting protrusion and at least one retaining rib , at least one first slot and at least one second slot communicated with the at least one first slot are formed on the booster seat , the at least one pivoting protrusion and the at least one retaining rib are accommodated in the at least one first slot when the seatback is located at an unused position relative to the booster seat , and the at least one pivoting protrusion and at least a portion of the at least one retaining rib are respectively accommodated in the at least one first slot and the at least one second slot when the seatback is located at a used position relative to the booster seat . a booster seat ; and a leg assembly detachably installed on the booster seat , the leg assembly comprising: at least one upper support detachably installed on the booster seat ; and at least one lower support detachably installed on the at least one upper support ; at least one upper support detachably installed on the booster seat ; and at least one lower support detachably installed on the at least one upper support ; wherein the child carrier is in a high chair mode when the at least one lower support and the at least one upper support are respectively installed on the at least one upper support and the booster seat to connect the leg assembly to the booster seat , the child carrier is in a youth chair mode when the at least one upper support is installed on the booster seat and the at least one lower support is detached from the at least one upper support , and the child carrier is in a booster mode when the at least one upper support is detached from the booster seat to separate the leg assembly from the booster seat , wherein the child carrier further comprises a seatback detachably installed on the booster seat ; wherein the seatback is rotatable relative to the booster seat ; and wherein the seatback comprises at least one pivoting protrusion and at least one retaining rib , at least one first slot and at least one second slot communicated with the at least one first slot are formed on the booster seat , the at least one pivoting protrusion and the at least one retaining rib are accommodated in the at least one first slot when the seatback is located at an unused position relative to the booster seat , and the at least one pivoting protrusion and at least a portion of the at least one retaining rib are respectively accommodated in the at least one first slot and the at least one second slot when the seatback is located at a used position relative to the booster seat . <EOS>