The invention relates to the technical field of a lift, in particular to a lift with a detection device for detecting displacement of a door ball of a lift hall door. The lift comprises a lift main body; the lift main body comprises a lift hall car door linkage device; the lift hall car door linkage device comprises a lift door opening machine arranged on a lift car as well as a landing door device arranged on the lift hall door; the lift door opening machine comprises a door knife; the landing door device comprises a door ball linked with the door knife and further comprises a photographing detection system; the photographing detection system comprises a photographing device and an image processing system; the photographing device is connected with the image processing system; the photographing detection system further comprises a shell; the photographing device and the image processing system are arranged in the shell; a light-transmitting opening is formed in the shell; the photographing direction of the photographing device faces towards the light-transmitting opening; the photographing direction of the photographing device faces towards the door ball through the light-transmitting opening; the shell is fixed on the door knife. The traditional photographing detection system for detecting displacement is arranged on the door knife, so that displacement monitoring of the doorball is realized.