A top cover for a headset of a bicycle includes a bottom ring, a side wall, a C-shaped clip and a fastening unit. The side wall extends upwards from the bottom ring. The C-shaped clip extends upwards from a top end of the side wall and has a through hole at each of two distal ends thereof. The fastening unit passes through the through holes of the C-shaped clip for tightening the C-shaped clip. Thus, the top cover of the present invention can enhance convenience of assembly and disassembly of the bicycle, and prevent components of the headset from getting lost during assembly and disassembly of the bicycle.