The present invention relates to a connecting structure of a lamp head base (2) and a lamp tube base (3). The lamp head base (2) includes an upper cover (21) and a lower cover (22) to engage with each other. The lower cover (22) has two troughs (221) which face downward and a through hole (222) disposed between the two troughs (221). A locking base (5) is connected to the lower cover (22). The locking base (5) includes a press surface (51) which is exposed outside an outer surface of the lower cover (22) and a hook (52) at an inner end thereof. The hook (52) is located above the through hole (222). The lamp tube base (3) includes two tubular sleeves (31) to fix two feet (41) which extend upward from a lamp tube (4), a connecting portion (32) to secure the two tubular sleeves (31), and a locking slot (33) disposed above the connecting portion (32). When assembling, the two tubular sleeves (31) and the connecting portion (32) of the lamp tube base (3) are respectively inserted in the two troughs (221) and the through hole (222) of the lower cover (22) of the lamp head base (2), and the hook (52) of the locking base (5) engages with the locking slot (33) of the lamp tube base (3).