Abstract: To address the problems of long testing periods, insufficient representativeness, and difficulty in continuously characterizing depth-dependent variations in the elastic modulus of weathered phyllite rock masses, a segmented rapid estimation method based on borehole acoustic testing is proposed. Based on borehole data of weathered phyllite in the western plateau region, engineering segments were determined by integrating geological logging and acoustic response characteristics, and representative P-wave velocities were extracted. The rock mass elastic modulus was estimated using RMR ratings and the Hoek-Brown criterion, and a relationship model between representative P-wave velocity and elastic modulus was established. The results show that the segmented RMR ratings range from 23 to 51, corresponding to Class III-IV rock masses. The representative P-wave velocity ranges from 0.8734 to 4.6768 km/s, and the rock mass elastic modulus ranges from 0.2111 to 3.7895 GPa, showing an overall positive correlation. Both the linear and power function models exhibit good fitting performance, with R² values of 0.9105 and 0.9089, respectively, whereas the exponential function model performs relatively poorly. Considering fitting accuracy, model form, and engineering interpretability, the power function model is recommended for rapid estimation of the elastic modulus of weathered phyllite rock masses. The proposed method provides a reference for rapid acquisition of mechanical parameters, engineering geological evaluation, and parameter selection of weathered rock masses.