[Objective] The permeability characteristics of the bedrock weathering layer were determined in order to propose a corresponding experimental method of hydraulic conductivity, and thereby provide a scientific reference for the performance assessment of underground engineering facilities in a porous and fractured medium. [Methods] We focused on granite at an underground engineering site in the southern coastal area of China. A tension infiltrometer was used to conduct the infiltration tests on the bedrock weathering layer. A nonlinear regression model, the White and Sully method, a multi-pressure method, and the Smettem and Turner method were adopted to calculate the hydraulic conductivity and carry out a comprehensive and comparative analysis. The spatial distribution of the hydraulic conductivity of the bedrock weathering layer was determined based on a geologic statistical method. [Results] ① The hydraulic conductivity of the fully weathered bedrock in this area was between 0.023 and 3.918 m/d, and the measured mean value was around 0.971 m/d, which was consistent with the empirical value. ② The permeability capacity of the bedrock weathering layer in this area was stronger in the high terrain area than in the low terrain area. ③ There were some differences in hydraulic conductivity obtained by using different calculation methods. ④ The multi-pressure method was more suitable for determining the hydraulic conductivity in the study area. [Conclusion] The hydraulic conductivity of the bedrock weathering layer in the study area was obtained by using a tension infiltrometer and the multi-pressure method. The permeability capacity of the bedrock weathering layer was found to be relatively weak.