A child carrier comprising: 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 at least one lower support comprises at least one first segment and at least one second segment detachably installed on the at least one first segment, wherein the child carrier further comprises a releasing module for allowing or restraining at least one of movement of the at least one second segment relative to the at least one first segment, movement of the at least one lower support relative to the at least one upper support and movement of the at least one upper support relative to the booster seat, wherein the releasing module further includes a leg releasing assembly for allowing or restraining movement of the leg assembly relative the booster seat, the leg releasing assembly includes four leg engaging components, four leg engaging slot structures, and four leg resilient components, the four leg engaging components are respectively movably disposed on the four upper supports, the four leg engaging slot structures are respectively formed on four sockets located on four corners of the booster seat, and the four leg resilient components bias the four leg engaging components to engage with the four leg engaging slot structures respectively, and wherein at least one third guiding portion is formed on an upper end of each upper support, at least one fourth guiding portion is formed inside each socket, the third guiding portion is cooperatable with the fourth guiding portion to guide the movement of the upper support relative to the booster seat to ensure the upper support to be installed into the socket properly. 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 at least one lower support comprises at least one first segment and at least one second segment detachably installed on the at least one first segment, wherein the child carrier further comprises a releasing module for allowing or restraining at least one of movement of the at least one second segment relative to the at least one first segment, movement of the at least one lower support relative to the at least one upper support and movement of the at least one upper support relative to the booster seat, wherein the releasing module further includes a leg releasing assembly for allowing or restraining movement of the leg assembly relative the booster seat, the leg releasing assembly includes four leg engaging components, four leg engaging slot structures, and four leg resilient components, the four leg engaging components are respectively movably disposed on the four upper supports, the four leg engaging slot structures are respectively formed on four sockets located on four corners of the booster seat, and the four leg resilient components bias the four leg engaging components to engage with the four leg engaging slot structures respectively, and wherein at least one third guiding portion is formed on an upper end of each upper support, at least one fourth guiding portion is formed inside each socket, the third guiding portion is cooperatable with the fourth guiding portion to guide the movement of the upper support relative to the booster seat to ensure the upper support to be installed into the socket properly.