Detailed measurements have been taken for the longitudinal turbulent intensities of flow in a gravel-bed flume. The experimental results indicate that the distribution of turbulent intensity greatly depends on the relative roughness. In comparison with the smooth-bed results, the roughness makes the flow turbulence become well-distributed, especially in the region near the bed and in the case of smaller H/K _s values. In addition, the cross sectional average of turbulent intensity is also discussed in this paper, and the results show that the roughness makes flow turbulence much more intense.