Abstract: This study aimed to explore rational topdressing fertilizer stage and types for summer maize in wheat- maize double cropping system in south of Shanxi Province. Effects of topdressing fertilizer stage (jointing stage and bell stage), and topdressing fertilizer types (urea and diammonium phosphate, and only urea) on the yield, water and fertilizer use efficiency of different summer maize varieties were studied, using splitsplit plot design. Results showed that, the variances of main plot, split plot and split-split plot were significant. The kernel number and 100-grain weight were the key factors affecting the yield of summer maize. Average yield and nitrogen fertilizer use efficiency (NFUE) of four maize varieties were‘Xianyu 335’＞‘Qiangsheng 51’＞‘Linyu No.3’＞‘Xundan 20’. Water use efficiency (WUE) of grain was‘Qiangsheng 51’＞‘Xianyu 335’＞‘Linyu No.3’＞‘Xundan 20’. For high-yield summer maize variety‘Xianyu 335’and‘Qiangsheng 51’, WUE and NFUE with topdressing urea and diammonium phosphate at jointing stage were higher than those of topdressing urea only. But topdressing urea at bell stage made the yield and water and fertilizer use efficiency higher than those of topdressing urea and diammonium phosphate. In wheat-maize double cropping system of south of Shanxi Province, topdressing urea and diammonium phosphate at jointing stage or topdressing urea at bell stage can achieve high yield and high efficiency of summer maize.