Abstract: The aim of this study was to investigate the effects of yak and Tibetan sheep trampling and rainfall on the soil characteristics in an alpine meadow. In a field experiment conducted in an alpine meadow in Tianzhu, Gansu Province, simulated trampling and rainfall treatments were applied and the soil physical properties and microbial population were analyzed. The results showed that the soil compaction and bulk density increased at 0-10 cm soil depth with increasing trampling intensity and precipitation, while the saturated hydraulic conductivity decreased. The soil respiration rate decreased with increasing trampling intensity. The soil respiration rate was decreased by 37% and 45% under heavy trampling intensity by yaks and Tibetan sheep, respectively, compared with that in the control. The soil respiration rate significantly increased with increasing precipitation (P<0.05). As the trampling intensity increased, the bacterial abundance first increased and then decreased, while the abundance of fungi and actinomycetes gradually decreased. The abundance of all three types of microorganisms increased with increasing precipitation, and the number of microorganisms decreased in deeper soil layers. Below the 0-10 cm soil layer, there was no significant difference in soil physical properties between the two trampling treatments (P>0.05). Under the same precipitation conditions, trampling by yaks had a greater compaction effect on soil than did trampling by Tibetan sheep. Soil compaction and bulk density were increased by 20% and 39%, respectively, by Tibetan sheep trampling, and by 23% and 44%, respectively, by yak trampling, compared with their respective values in the control (untrampled). The magnitude of the increase in soil respiration rate, saturated hydraulic conductivity, and abundance of all three types of microorganisms were all lower under yak trampling than under Tibetan sheep trampling treatments at the same grazing intensity. Overall, soil physical properties and microbe abundance were strongly affected by increased livestock trampling and soil moisture. The soil physical properties at 0-10 cm depth were strongly affected by livestock trampling, and yaks caused greater soil compaction and more negatively affected microorganism distribution than did Tibetan sheep.