[Objective] The effects of rainfall intensity on the happening of overflowing and breaking on basin tillage and the relevant variations of basin tillage's soil and water conservation efficiency were explored to provide references of suitable requirements for the application of basin tillage and for the evaluation of its soil and water conservation efficiency. [Methods] Simulated rainfall was applied on two tillage patterns of basin tillage and compared conventional tillage, and to analyze their processes of soil and water production and the variations of soil and water conservation efficiency. [Results] When rainfall intensity was under 60 mm/h, there was ridge overflowing occurrence but no damage or breaking for basin tillage, and the efficiency decreased slightly. When rainfall intensity was over 60 mm/h, damage and breaking occurred as soon as overflowing happened, whereafter the efficiency decreased remarkably. Average runoff conservation efficiency was 87.5% and the soil conservation efficiency was 88.2%. When basin tillage was damaged, the above two items decreased to 34.1% and 21.0%, respectively. [Conclusions] Basin tillage would remain good efforts on soil and water conservation when rainfall intensity under 60 mm/h. When it is over 60 mm/h, because dams of basin tillage might be broken down easily after overtopping, it would lost its ability of blocking water and soil, and hence relevant conservation efficiency decreased remarkably as well.