The rain garden infiltrates and purifies rainfall runoff through the comprehensive effect of “plant-soil-microorganism”; however, the clogging of fillers leads to the decrease of its hydraulic conductivity with the extension of operation time, resulting in the attenuation of the rain garden operation life. Taking the rain garden of infiltration type which has been operating for ten years and its surrounding conventional green space in Xi’an University of Technology as the research objects, we studied the influencing factors of the hydraulic conductivity attenuation of the rain garden by comparing the total pollution load of these two facilities, the infiltration rate of the fillers and the particle size distribution of different layers. The results showed that the main pollutants in the rain garden are SS, TN, TP and COD, and the total inflow loads are about 544.51, 21.55, 1.65 and 514.50 g/m2, which are 7-34 times of those in the conventional green space. At present, the steady infiltration rate of the conventional green space is nearly 10 times of that of the rain garden. From the temporal perspective, the steady infiltration rate of the rain garden after 10 years of operation is 23.24 mm/h, which is 5.2 times lower than that in the initial stage of establishment. Compared with the conventional green space on vertical spatial scale, the content of clay and powder particles in the rain garden fillers with the buried depth of 0-50 cm are relatively high; whereas the particle size distribution of the two facilities buried deeper than 50 cm are basically the same, indicating that the phenomenon of clogging mainly occurred in the fillers with the buried depth of 0-50 cm. Finally, the prevention and control measures of clogging are put forward, according to the precipitation conditions and operation mechanism of the rain garden.