Abstract: Physical fracturing experiments on coal-rock masses serve as a critical validation method for theoretical models and numerical simulations while providing technical guidance for industrial applications. Current limitations persist in comparative studies of different fracturing fluids and internal fracture propagation monitoring. A multifield multiphase fracturing apparatus was developed to investigate fracture extension mechanisms under multiphase fluid injection (liquid, gaseous, supercritical) within stress-fracture-seepage coupled fields. The system comprises four key modules: high-pressure fluid injection, true triaxial hydraulic servo-loading, backpressure metering, and multi-channel data acquisition. Key features include: ① Independent fluid delivery circuits connecting guanidine gel, water, N₂, and SC-CO₂ to either KDHSH100 dual-cylinder precision pumps or gas boosters; ② 40 MPa maximum injection pressure, 50 MPa triaxial loading capacity (X/Y/Z directions), and 300 mm×300 mm×300 mm specimen compatibility; ③ Acoustic emission (AE) signal analysis integrating time-domain, frequency-domain, and spatial parameters for fracture characterization. Using this device, true triaxial fracturing tests were conducted with four fluid media: guar gum aqueous solution, pure water, N₂, and SC-CO₂. The time domain-frequency, domain-spatial domain response laws of acoustic emission during the fracturing process of different fluid media were revealed, and the multi-information of acoustic emission such as pump injection pressure, fracture morphology, ringing count, frequency and amplitude in the frequency domain, and spatial location were analyzed. The test results show that among the four media, SC-CO₂ generated the highest density of secondary fractures. Liquid injection maintained stable AE ring-down counts with dominant high-frequency components ( > 78% HF content), whereas non-liquid media exhibited abrupt AE count surges near fracture initiation pressure, attributed to compressibility-induced pressure accumulation in low-permeability specimens. Spatial AE events were predominantly observed during pressure stabilization phases (liquid fracturing), gradual pressurization/rapid depressurization stages (N₂ fracturing), and concentrated rapid depressurization phases (SC-CO₂ fracturing).