Abstract: Indoor human activity is an important factor of indoor particulate matter resuspension, and the study of indoor particulate matter resuspension is of great significance to the evaluation of indoor air quality. A public classroom in Jinnan campus of Nankai University was taken as the research area. The resuspension concentration and diffusion rate of the human walking-induced indoor PM_2.5 resuspension under different dust loads of indoor ground were studied by field experiments. The results show that: (1) When the time interval is 3, 7 and 15 days, the indoor PM_2.5 dust load is 0.11, 0.18 and 0.30 g/m², respectively. (2) The concentration of the human walking-induced indoor PM_2.5 resuspension in the indoor center aisle reaches the maximum value at about 1 min for different dust loads of indoor ground. The relationship between the time when PM_2.5 resuspension concentration reaches the maximum value and the different dust loads on the ground is not obvious. (3) With the increase of indoor dust loads, the concentration of the human walking-induced indoor PM_2.5 resuspension will also increase. When the indoor PM_2.5 dust load was 0.30 g/m², the average concentration of PM_2.5 resuspension for breathing plane at 1.1 m sitting position and 1.5 m standing position was 3.03 and 2.68 μg/m³, respectively, which was about 2-3 times of the average concentration of PM_2.5 resuspension for PM_2.5 dust loads of 0.18 and 0.11 g/m². (4) The quantitative analysis of PM_2.5 resuspension by using particle transport model shows that the magnitude of dust loads don't affect the resuspension fraction of PM_2.5, and the resuspension fraction of PM_2.5 is 2.2×10^-8. When the indoor PM_2.5 dust loads is 0.11, 0.18, 0.30 g/m², the diffusion rate of the human walking-induced indoor PM_2.5 resuspension is 7.62×10^-11, 1.25×10^-10 and 2.08×10^-10 kg/s, respectively. The dust load on the ground will affect the diffusion rate of particulate matter and indoor PM_2.5 concentration.