As one of the most importance ways for supporting herds of domesticated ungulates, grazing is the simplest and most effective way of grassland utilization. The effects of grazing on grassland ecosystem are also one of the classic topics of animal ecology. In recent decades, overgrazing has caused serious grassland degradation. Although some studies have focused on the effects of grazing on grassland ecosystems on the Qinghai-Tibetan Plateau, little information on the effects of yak grazing intensity on alpine grasslands are revealed based on long-term in situ field observations, especially for experiments with more than 4 years. In this study, we selected a typical alpine meadow in the eastern of the Qinghai-Tibetan Plateau and used yaks as our large herbivorous livestock because yaks are unique and most widely distributed on the Qinghai-Tibetan Plateau. According to local investigations and pre-experiment, we set up four yak grazing intensities (no grazing; light grazing, 1 yak/hm²; moderate grazing, 2 yaks/hm²; and heavy grazing, 3 yaks/hm²) to examine their effects on soil properties and plant growth in a typical alpine meadow of the Qinghai-Tibetan Plateau. After continuously conducting four-years experiment, we found that soil water content increased significantly under grazing treatments. Soil bulk density, total phosphorus (P) content and organic matter content showed no significant responses to grazing intensities. Soil total nitrogen (N) content was significantly higher under light and heavy grazing than that under moderate grazing at the top soil of 0-20 cm. Conversely, soil pH was significantly higher under moderate grazing than light grazing at the top soil of 0-20 cm. Soil total potassium (K) content under no grazing was significantly higher than that under grazing treatments. Soil available N and K contents were only significantly higher under moderate grazing than those under no grazing. Grazing also significantly reduced aboveground biomass of plants. In short, yak grazing intensities significantly altered soil water content, soil available N and K contents, and plant aboveground biomass, while they had weak effects on soil organic matter, total N, and total K contents. This study reveals the effects of grazing on soil physiochemical properties and plant aboveground biomass in a typical alpine meadow, though further study should be required to investigate the influences of long-term grazing experiments on the interactions of plants and soil and determine appropriate grassland managements in a long term based on our yak grazing experiments. Overall, this study provides basic data for the protection, sustainable management and reasonable grazing rate of alpine meadow ecosystem on the Qinghai-Tibetan Plateau.