Based on the temperature and acoustic impedance sensing theory utilizing forward stimulated Brillouin scattering （FSBS） in aluminum-coated optical fibers， the influence of coating thickness on acoustic mode frequency and linewidth was investigated， simultaneous measurement of temperature and acoustic impedance was realized， and an innovative high-sensitivity method for disease detection in blood was proposed. The simulation results demonstrated linear relationships between the frequency/linewidth variations of radial acoustic modes R_0，m with temperature and acoustic impedance. Fibers with different coating thicknesses exhibited distinct different sensitivities. The optimal linewidth-based acoustic impedance sensitivity is of 3.90 MHz/（kg·mm²·s） at 3 µm coating thickness and maximum frequency-based temperature sensitivity reaches up to 51.44 kHz/℃ at 5 µm coating thickness. Measurement errors can be reduced to 0.015 ℃ and 0.033 kg/（mm²·s） for 3 µm coating， and 0.008 ℃ and 0.027 kg/（mm²·s） for 5 µm coating， respectively. Taking ±0.5 μm coating thickness variation into account， the temperature and acoustic impedance tolerance vary within 0.003-0.020 ℃ and 0.021-0.032 kg/（mm²·s） for 3 µm coating， and 0.003-0.009 ℃ with 0.004-0.058 kg/（mm²·s） for 5 µm coating， respectively. This sensing system enables real-time monitoring of blood temperature and acoustic impedance， demonstrating potential applications in distinguishing normal physiological states from pathological conditions （e.g.， hyperproteinemia， anemia） through multi-parameter analysis. The technology may provide innovative solutions for early disease diagnosis and precision medicine through its high-sensitivity detection capabilities.