A locking assembly is adapted for connecting a first respiratory tube and a second respiratory tube. The first respiratory tube has an outer surrounding surface. The locking assembly includes a sleeve and a coupling unit. The sleeve is adapted to be sleeved fittingly on the first respiratory tube and has an inner surface, an outer surface, and a first locking portion. The coupling unit includes a connecting tube and a locking component that has a second locking portion. The second locking portion is pivotable relative to the connecting tube between a locked position and an unlocked position.
