In order to explore the effect of freezing and thawing on the rainfall erosion on the slope, a freezing and thawing experiment was conducted in Xi'an, and the characteristics of rainfall erosion on slopes with different water content were studied in the experiment. The results showed that the emergence flow time increased first and then decreased with the increase of the initial water content, and the emergence flow time was delayed by freezing and thawing, specifically, the lag was up to 62.50% when the water content was 20%. The runoff flow on the completed thawed slope with 20% water content was 9.14% lower than that of unfrozen slope（P＜0.01）；the sediment yield on the completed thawed slope with 20% and 25% of the water content decreased by 28% than that of the unfrozen slope（P＜0.01）.In summary, it can be concluded that the effect of freezing and thawing on the runoff time and runoff process was the most obvious when the water content was 20%, while the effect of freezing and thawing on the sediment yield and erosive K value was the most obvious when the water content was 20% and 25%. When the water content was 20%, the sediment yield was the smallest and the erosibility was the lowest, hence, 20% can be used as the optimal water content of loess.