CHILD RESTRAINT SYSTEM AND ADJUSTABLE HEADREST ASSEMBLY THEREOF

A child restraint system is provided. The child restraint system includes a main body and an adjustable headrest assembly. The adjustable headrest assembly is installed on the main body. The adjustable headrest assembly includes at least one rail and a head support portion. The at least one rail is movably disposed on the main body and movable between a lower position and an upper position relative to the main body. The head support portion is movably disposed on the at least one rail. Besides, a related adjustable headrest assembly is provided.