[Objective] The characteristics of rainfall were analyzed and the simple algorithm of rainfall erosi-vity of West Guizhou plateau area were studied to provide theoretical basis for the building of the soil erosion prediction model. [Methods] 53 rainfall events of Bijie area from 2012 to 2014 were obtained by means of runoff plots observation. [Results] The results showed that: (1) rainfall amount(P) and rainfall energy of 60 minutes(E₆₀) were two important affecting factors on the processes of slope runoff and sediment. Slope runoff and sediment yield were found significantly correlated with rainfall intensity of 60 minutes(I₆₀). (2) The correlation coefficients between runoff/sediment and the mixed factors of rainfall indicated that EI₆₀, PI₆₀ and I₃₀ I₆₀ were three kinds of the most important impacting factors on soil erosion process. What is more, the correlation coefficient between runoff/sediment and EI₆₀ was slightly different with the one between runoff/sediment and EI₃₀. (3) Parameters of simple algorithm of rainfall erosivity were determined based on the above analyses. [Conclusion] Through the comparison of determination coefficients and the average error rates obtained from three algorithms, the simple algorithm of rainfall erosivity of the study area was expressed as R=0.344(PI₆₀) with reference to R=EI₃₀ for its comparability.