The pressure-stimulated rock current (PSRC) is an extremely important petrophysical phenomenon and the catastrophic characterization of solid Earth, which attributed to several physical mechanisms including dislocation and positive holes (Ph). The micro-crack development coupling with the two mechanisms runs through the whole process of loading rock to failure, but how its development and type affect PSRC has not been well studied so far. The acoustic emissions (AE) and PSRC between the loaded part and free part were detected synchronously when bi-axially load dried diorite specimens to failure. This study revealed the remarkable characteristics of staged-variation of PSRC: a low-stable fluctuation in the elastic stage, accompanied with an instantaneous step-rising of average 26.6 nA; then exhibited stead fluctuation at the step until failure, accompanied with a negative pulse of several hundred nanoampere. The little PSRC in the elastic stage was mainly attributed to the Ph activated by tensile micro-cracks; while the step-rising large PSRC was attributed to the sudden rising of number and ratio of shear micro-crack at the moment of elastoplastic transition; after that, the PSRC was generated mainly by the coupling of continuous massive Ph activation and dislocation sliding resulting from shear micro-cracks. A quantitative expression was established to describe the PSRC dynamics. The results enriched and refined the mechanisms of PSRC, which provide key basis for engineering rock mass monitoring and critical status scrutinizing, and are of reference meanings for the monitoring of seismic electrical, magnetic and related radiation as well as the identification of earthquake precursors.