Abstract: Abstract: This study aims to explore the effects of grazing and rodent damage on the soil physical and mechanical properties of alpine degraded grassland in the source region of the Yellow River. The alpine grassland in Henan County, Qinghai Province, China was selected as the study area. Three influence conditions were set, including the no-pika condition (Rodents, cattle and sheep were prohibited from eating and trampling), no-grazing condition (Cattle and sheep were forbidden to eat and trample, while rodents were allowed to eat and trample), and natural condition (Rodents, cattle and sheep were allowed to eat and trample) in this region. Four degradation types were divided into: the non-degraded, slightly, moderately, and heavily degraded grassland. Some parameters were measured, including the soil moisture content, density, root content, cohesion and internal friction angle of four degraded grasslands under three influence conditions. An analysis was made on the variation characteristics of soil physical and mechanical properties. The one-way analysis of variance (ANOVA) was utilized to evaluate the parameters under various influence conditions and degradation types. A nonparametric Wilcoxon test was carried out to determine the effects of three influence conditions on the internal friction angle of soil without considering degradation types. A grey correlation analysis was implemented to clarify the effects of soil moisture content, density and root content on the cohesion of soil in four degraded grasslands. The results showed that the soil moisture content, root content, and cohesion decreased gradually, whereas, the soil density increased gradually with the aggravation of grassland degradation. By contrast, there was less outstanding change in the internal friction angle of soil with the aggravation of grassland degradation. The cohesion of soil was ranked in the descending order under the same degradation type: no-pika, no-grazing, and natural condition. The internal friction angle of soil was ranked from large to small: no-grazing, no-pika, and natural condition. Among them, the cohesion of soil under no-pika condition was significantly higher than that under natural condition (P<0.05). Regardless of grassland degradation types, the internal friction angle of soil under no-grazing condition was significantly higher than that under natural condition (P<0.05). Therefore, the rodent and grazing prohibition can improve soil cohesion and internal friction angle of grassland. In addition, there was the relatively high correlation between the cohesion of soil and root content, ranging from 0.706 to 0.778 for the non-degraded and slightly degraded grasslands. There was the relatively high correlation between the cohesion of soil with the density and moisture content for the moderately and heavily degraded grasslands. Specifically, the correlation degrees were 0.586-0.785 and 0.622-0.779, respectively. The results can also provide the theoretical reference and practical guiding significance to effectively prevent the occurrence of natural disasters, such as the soil erosion and shallow landslide that caused by the degradation of alpine grassland in the source region of the Yellow River.