The invention discloses a mortise door lock handle locking device, connecting the mortise door lock body part and comprising a fixed panel and a turning handle which is arranged on the fixed panel and drives a lock tongue to move. The locking device is characterized in that a blocking rotary vane is arranged on the turning handle and a press locking mechanism movably jointed with the blocking rotary vane is arranged on the periphery of the blocking rotary vane; the press locking mechanism comprises a locating block, a button and an elastic reset part; the locating block is connected at the end of the button; a plurality of blocking positions corresponding to the locating block are arranged on the edge of the blocking rotary vane. The locking device has low failure rate and compact structure, safe and reliable operation, convenient use and good popularization value and resists prying, drilling and deciphering.