Turbulence modulation by particles in a fully-developed channel flow was investigated by Lagrangian measurement technique. Digital particle image velocimetry and a high-speed CCD camera mounted on a shuttle moving with particle mean streamwise velocity were used to simultaneously detect particle and fluid information amongst particles. Turbulence augmentation by particles greater than the Kolmogorov micro scale was induced by the region of the high-strain rate and high vorticity on both sides of particles. The Rapid Distortion Theory first applied to dispersed two-phase turbulent flows indicated that the directional non-isotropic structure was observed with an increase in particle volumetric fraction. The enstrophy amongst particles increased due to enstrophy production with a decrease in inter-particle spacing.