Abstract: The velocity fields in particle-laden two-phase round turbulent jets were measured by means of phase Doppler particle analyzer(PDPA).The turbulence modulations caused by the change of particle size and particle mass loading ratio were studied under the condition of small particle Reynolds number.The measured results of turbulence intensities show that particles have more pronounced effects on the attenuation of the gas-phase turbulence, if the particle diameter reduces, or the particle mass loading ratio increases.The dimensionless analysis shows that the attenuation of turbulence intensity introduced by decreasing the particle size is higher than that by increasing the particle mass loading ratio.