Abstract: A locking device is provided for a collapsible luggage trolley of the type having a pair of outer tubes, a pair of inner tubes respectively, telescopically received in the outer tubes, and an operative handle connected to upper ends of the inner tubes. The locking device includes a rack formed on the inner periphery of one of the outer tubes. A rod is mounted in one inner tube which is telescopically received in the outer tube. The rod includes an upper end operably connected to the operative handle to move therewith. A latching device includes a link having an upper end securely connected to a lower end of the rod to move therewith, a plate member mounted to a lower end of the link and including two lateral walls each having an inclined slot defined therein, and a latch block including two protrusions formed on two lateral sides thereof and slidably received in the inclined slots of the plate member, respectively.