The invention relates to the technical field of geological engineering monitoring, and provides a displacement automatic measuring device for a slope crack. The measuring device comprises a vibratingwire type displacement meter, a first torsion type resistance strain meter, a second torsion type resistance strain meter, a crack displacement processing module, a first fixing anchor column, a second fixing anchor column and a wireless communication module. According to the automatic displacement measuring device, vector displacement in three directions of the slope crack can be measured at thesame time through the vibrating wire type displacement meter and the two torsion resistance strain gauges, and then the actual deformation activity state of the slope crack can be reflected more comprehensively, accurately and reasonably. The vibration wire type displacement meter and the torsion type resistance strain gauge are used for measuring the displacement of the slope crack, the advantages of being sensitive in reaction and high in precision are achieved, the vibration wire type displacement meter and the torsion type resistance strain gauge are installed on the fixing anchor columns,the problem that a traditional embedded sensor is prone to damage is solved, and the stability and reliability of the whole measuring device are improved.