Abstract: The loess plateau is a serious disaster area with frequent landslide accidents in China, and rainfall is one of the main factors influencing instability of loess slopes. Therefore, it is particularly important to learn the law and mechanism of rainfall infiltration inside the loess slopes. The interior slope rainfall model box and artificial rainfall system are designed, a wild homogeneous loess slope is selected which is belonged to the Qingyang region of Gansu Province as the research object, a laboratory scale homogeneous loess slope model is established under the condition of meeting the similarity theory, and rainfall infiltration test at slope ratio 1:1 under four different rainfall intensities are carried out. The laws of model slope about rainfall infiltration and variation characteristics of matrix suction are analyzed by monitoring the volume moisture content of the slope and matrix suction in the whole course, and the difference of infiltration laws of model slope under different rainfall conditions is compared. The experimental results show that under different rainfall conditions, the infiltration depths of the loess model slope all present the rules which the depth of the foot of the slope is the greatest, the top of the slope which the second greatest, and the middle of the slope is the smallest, while the infiltration rate is that the top of the slope is the largest, the foot of the slope is the second greatest, and the middle of the slope is the smallest. With the increase of the depth, the infiltration capacity of rainwater gradually decreases. With the increase of the rainfall intensity, the greater the depth of rainfall infiltration is and the faster the infiltration rate is, the more significant the amplitude of variation volumetric moisture content and matric suction which are buried at the same depth are.