Abstract: The present invention relates to a method for calibrating a focus position of an optical pick-up. The optical pick-up is located on a focus position at a preset distance from a recordable optical medium to emit a recording beam of a preset power to the recordable optical medium so that corresponding optical data are recorded in the recordable optical medium. The method includes: altering a focus position of the optical pick-up during a recording process to generate a corresponding write radio frequency (RF) signal; detecting a minimum value of the write RF signal and a corresponding object focus position; and moving the optical pick-up to the object focus position so that the optical pick-up performs recording at the object focus position in the recordable optical medium.