A collapsible canopy with an improved locking mechanism. The collapsible canopy has at least three supporting legs. The collapsible canopy also has a self-locking central lock that is used for locking the collapsible canopy in an unfolded state and permits the collapsible canopy to be folded into a folded state when the central lock is unlocked. An outer retractable unit is connected between each adjacent supporting leg. An inner retractable unit having an inner end is connected between each supporting leg and the central lock. The inner end of the inner retractable unit is connected through the central lock.