To reveal the mechanisms of soil erosion by sheet flow is important for the understanding of erosion processes on loess slope. With artificially simulated rainfall tests, sheet flow erosion processes on loess hill slope are studied and the follow ing results are obtained: ( 1) Under different rainfall intensities, sheet flow erosion varied similarly with rainfall process and can be described with power functions. Sheet flow erosion increased with rainfall duration increasing. ( 2) Under different slope gradients, sheet flow erosion increased with rainfall intensity increasing and can be described by linear equations. ( 3) Under different rainfall intensities, sheet flow erosion modulus increased firstly and then decreased with soil gradient increasing. Their relationship can be described by log-linear equations. ( 4) Under different rainfall intensities, the relationship can be descried by power equations. ( 5) Under different rainfall intensities, slope gradients, and slope lengths, sheet flow erosion can be described by ternary linear equations. Rainfall intensity affected erosion modulus most greatly, followed by slope gradient, and slope length behaved minimal impacts.