The invention belongs to the technical field of rock mass permeability measurement, and relates to a method for observing fracture permeability of variable-pressure adjustable rock mass. The connection relationship of the device used is as follows: a converter thread is connected to the rear part of a front plugger, and the inner part of the converter thread comprises an inner ring, a spring and across wire sleeve, the compression degree of the spring is changed by adjusting the cross wire sleeve, and the pressure-on of the inner ring is further controlled; after the front plugger and the tail plugger are expanded, a water injection cavity is formed with a drilling hole, and the external high-pressure water enters the water injection cavity through the converter to detect the permeabilityof the drilling hole. The testing device simplifies the external operating system and the operation steps, reduces the pipe in the drilling hole to be one, avoids the problem of the wire winding of the drilling rod, improves the stability of the measuring process, realizes the sealing process and the measuring process under the own respective pressure with the same water source, the variable pressure regulation of the converter is realized, so as to adapt to different working environment and pressure-on demand.