In combination of field investigation with laboratory analysis,the relationships between multiple cropping and soil and water loss in the purple soil region were analyzed using soil erodibility Kvalue,runoff and erosion amount as indicators.Results showed that:(1)In contrast to single cropping pattern,the different cropping modes enhanced the sensitivity to soil and water loss,increased soil erodibility Kvalue and made soil to be eroded more easily.(2)The K value had a significantly negative correlation with sand content,with a correlation coefficient of-0.957.It was negatively correlated with clay content and organic C content,with correlation coefficients of-0.191and-0.637,respectively.The Kvalue had a significant positive correlation with silt content,with a correlation coefficient of 0.986.The levels of organic matter content and clay content were the sound indexes reflecting the resistance to erosion for purple soil.(3)Compared with the grapefruit pure cropping pattern,the runoff interception efficiency by multiple cropping was significant.The multiple cropping pattern of grapefruit and Pachyrhizua angulatus has the best effect in controlling soil erosion and thus is most suitable for application.