Abstract: In order to investigate the parameter effects on the pebble dynamics in the high-temperature reactor core where the fuel pebbles and graphite pebbles form two regions,based on the two-dimensional pebble-dynamics experiments,the discrete element method（DEM） was used to simulate the pebble-dynamics and phenomenological method was used to analyze the two-region arrangement,the size and shape of the central pebble column,the dispersion in the mixing region and the stagnant regions at different friction coefficient and different cone angle.The results show that with the increasing of the friction coefficient,the ball flow tends to more uniform,the stagnant zone increases and the mixing zone decreases.While the cone angle increases,the flow seems more even,the stagnant zone and the slow zone decrease.