Vegetation cover is an important factor in the process of soil erosion. This paper revealed the changes of photosynthetic vegetation coverage (f_PV) for meadow steppe, typical steppe and desert steppe in Inner Mongolia from 2002 to 2016 and their responses to precipitation in the annual, seasonal, and monthly scales. The MODIS derived data and corresponding precipitation data were used in the analysis. The results showed that: (1) from 2002 to 2016, the annual average f_PV of three steppe types was 46.5%, 36.3%, and 22.4%, respectively. The trend of f_PV over time for all three steppe types was not significant. For meadow steppe the annual change was positive with a rate of 0.29% per year, while for typical steppe and desert steppe it was negative with the rate of -0.04%/a and -0.21%/a, respectively. The annual precipitation for the three steppe types all showed an increasing trend without statistical significance. (2) The monthly vegetation coverage was clearly affected by the prior one to two month precipitation, and the cumulative effect was also evident. The more arid the steppe type, the more obvious of the lag effect. The coverage of dessert steppe was comparatively more sensitive to the change of precipitation. (3) The annual vegetation coverage of three steppe types in Inner Mongolia was significantly affected by the annual precipitation, growth season precipitation, and the precipitation in June, July, and August. The linear regression between the annual vegetation coverage and the precipitation in the growth season showed a good fit. The significant correlation between annual vegetation coverage and precipitation of three steppe types in Inner Mongolia provides a scientific basis for dynamic, regional soil erosion assessment.