Abstract: Gravel mulch technique can reduce soil moisture evaporation, some of the world’s arid and semi-arid areas have been varying degrees of application. However, the mulch will also retain a certain degree of rainfall when raining and rain water into the soil passing through the gravel mulch. The simulated rainfall experiments were carried out. The results indicated that the amount of water absorption of baked gravel increasing as the rainfall duration prolonging, and gradually reach the saturated water adsorptive value under the same conditions with the same rainfall intensity, rainfall duration prolonging, gravel paving pattern; The rainfall duration of baked gravel gotten to the saturated water adsorptive value was shortened as the gravel average equivalent diameter reducing. Rainfall interception and water retention among particles in gravel mulch gradually reduced an the gravel average equivalent diameter increasing. The relation between rainfall interception and gravel average equivalent diameter was fitted by Exponential Decay Model as the gravel average equivalent diameter increasing. The data fitted was highly significant.