Abstract: In order to evaluate the differences of rice-stem lodging resistance between controlled irrigation and regular irrigation, and seek irrigation treatment which was beneficial to rice stem lodging resistance, rice-stem was taken as the research object, and the performance of rice-stem lodging resistance was studied under different irrigation treatments. Stem coefficient was introduced, and the mechanical analysis of rice-stem was carried out. The differences of lodging resistance ability under two kinds of controlled irrigations and one kind of regular irrigation were compared. The result showed that the values of internode plumpness of rice stem under controlled irrigations were bigger than that under regular irrigation, and the values of wall thickness of rice stem under KI and KII were much superior to that under regular irrigation by 0.15 mm and 0.35 mm. It also pointed out the values of rice stem coefficient under controlled irrigations were lower than that under regular irrigation, the order was CK＞KI＞KII, while the order of critical force was KII＞KI＞CK. Therefore, the rice stem under controlled irrigation is much better at lodging resistance.