Abstract: Based on laboratory sand falling device and particle flow software PFC^2D, we study the effects of particle size and friction coefficient on the pressure characteristics of sand accumulation structure. In the laboratory test, we select dry sand, wet sand, wet sand+loess to analyze the effects of particle size and inter-particle friction coefficient on the bottom pressure of the sand heap. We use the built-in command of PFC software(ball generate) to generate particles with three different particle sizes and used its ball property command to assign six different friction coefficients to the particles. In addition, we analyze its influence on the internal structure of sand heap from the perspective of force chain. The results show that particle size and inter-particle friction coefficient have significant influence on the bottom pressure of this structure. Under the condition of the same friction coefficient, the larger the particle size, the more sparse the distribution of the contact force chain, and the smaller the bottom pressure. Under the condition of the same particle size, the bottom pressure of sand heap decreases first and then tends to be stable with the increase of friction coefficient. That is, the influence of friction coefficient on the bottom pressure of sand heap has an upper limit.