The present invention discloses a bicycle hub speed-change assembly having a planetary gear set disposed therein, a speed-change gear wheel separately disposed on both left and right sides of the planetary gear set, and a first ratchet jacket and a second ratchet jacket respectively disposed on the external side of the speed-change gear wheels, such that control ratchets of the first ratchet jacket and second ratchet jacket are selectively hidden or driven by an external ring of the planetary gear set to couple the first ratchet jacket with a hub, so as to provide three different speeds and the invention features the advantages of stable speed, simplified components, and light weight.