In the present study, multiple regression equation and surface response analysis were used to investigate the effects of soil bulk densities and water contents on the amount and rates of disintegration in a purple soil. The results showed that:(1) Under the same bulk density, the amount of soil disintegration decreased with the increase of water contents, and the soil disintegration time varied with water contents. The total time of soil disintegration was extended with the increase of water contents, and the amount of soil disintegration was mainly concentrated in the first three minutes of the soil disintegration stage. (2) Under the same water content, the amount of soil disintegration decreased but the soil disintegration time increased with the increase of soil bulk densities, and the amount of disintegration was mainly concentrated in the first four minutes. (3) Under the same bulk density and water content, the soil disintegration rates decreased with the increase of soil bulk densities and water contents. Compared with bulk density, water content had a greater influence on the soil disintegration rates. The interaction of bulk density and water content had a significant effect on the soil disintegration rates, indicating that the soil disintegration rates decreased with the increase of bulk density and water content. Our findings provided some reference for controlling erosion of the purple soil.