The invention discloses a freely combined lamp wick of a flip-chip power light emitting diode (LED) tube core. The freely combined lamp wick comprises flat flip-chip soldering GaN-based LED tube cores and heat conducting substrates; a P soldering plate is made at the outer end of a P electrode soldering joint of each of the flat flip-chip soldering GaN-based LED tube cores; and an N soldering plate is made at the outer end of an N electrode soldering joint. The freely combined lamp wick is characterized in that: a P electrode region and an N electrode region which are connected in series or in parallel and needed for the making of the combined lamp wick are photoetched on one heat conducting substrate; and each flat flip-chip soldering GaN-based LED tube core is soldered to the P electrode region and the N electrode region of each of the heat conducting substrates through the P soldering plate and the N soldering plate in an eutectic or alloy manner. The substrate is soldered by the flat flip-chip alloy or eutectic of the metal soldering plate; the substrates can be randomly assembled and connected according to the requirement of the lamp wick by a photoresist etching or peeling method; channels are made on the substrates by photoresist etching or peeling according to requirement to connect the chips, so the shortcoming of routing connection can be avoided and the step of integrating the routing connection among the tube cores is eliminated; furthermore, the freely combined lamp wick is easy to manufacture and the finished product ratio is improved simultaneously.