Abstract: An auto-control system for rainfall simulation system with advanced auto-control theory and technique was researched and developed. In this system, a final and factual rainfall parameter was used to control and drive every part of apparatus, which reduced the random effect of different steps from pond to spraying nozzle. The results showed that this system was precise enough to simulate rainfall processes with different amounts, durations and densities for different research purposes, and its main function criteria were better than other domestic systems.