In order to systematically study the effects of nitrogen fertilizer operation and chemical regulators on the yield and lodging resistance of double-cropping rice, this study used early rice varieties Luliangyou 996 and Zhuliangyou 819, and late rice varieties Hyou 518 and Shengtaiyou 018 as materials, field experiments were carried out with different nitrogen fertilizer operation methods(amount ratios of tillering fertilizer, ear fertilizer and grain fertilizer, N1, N2 and N3 were 7∶2∶1, 6∶3∶1, 5∶4∶1 respectively) and chemical regulators(C1 and C2 were paclobutrazol and chitosan oligosaccharides). The results showed that nitrogen fertilizer operation and chemical regulation had a significant impact on rice yield, and the yield of early and late rice varieties was the highest under N2C2 treatment, mainly through increasing the effective panicle number of plants. Compared with N1 treatment, N2 and N3 treatments decreased stem height, internode length and center of gravity height, increased stem thickness, stem wall thickness and internode fullness, enhanced stem lodging resistance, and N2 was better than N3 treatment. Compared with C3, both C1 and C2 reduced rice stem height, center of gravity height and internode length, and increased stem thickness, stem wall thickness and internode fullness, thereby improving rice lodging resistance. In the view of interacting effects, the N2C1, N2C2 and N3C1 treatments had larger stem diameter and stem wall thickness, shorter internodes between inverted 3 and inverted 4, higher internode fullness and bending resistance, and lower lodging index. Considering the lodging index and yield traits of each variety comprehensively, N2C2 treatment, which used spraying chitosan oligosaccharides at the early jointing stage under the condition of 6∶3∶1 ratio of tillering fertilizer, ear fertilizer, and grain fertilizer, could improve the lodging resistance of double-cropping rice and obtain the highest yield at the same time.