UPLC-ELSD was carried out to simultaneous determination of fructose, glucose, sucrose and maltose in maize seed. UPLC-ELSD was utilized with a mobile phase with 75 % （v/v） acetonitrile containing 0.2 % （w/v） triethylamine. In addition, the flow rate of mobile phase was 0.2 mL/min and the column temperature was set to 35℃. The obtained regression equation revealed a good linear relationship between 0.9993 and 0.9999. The proposed UPLC-ELSD method was validated for quantification of fructose, glucose, sucrose and maltose in maize endosperm and embryo during imbibition. The results showed that the content of four sugars various in both organs. In endosperm, the content of sucrose reached a minimum at 48 h imbibitions. The contents of fructose and glucose showed similar, displaying a steady rise during imbibition. However, maltose could be detected in 48 h. In dry embryos, the contents of four sugars could be detected and more than in endosperm. During imbibition, the contents of sugars in embryos showed very similar profiles to in endosperms. Taken together, these results might suggest that sucrose degraded to glucose and fructose in the beginning of imbibitions. Prolong with imbibition, reserve substance degraded into sucrose, maltose, glucose and fructose, providing carbon source for the maize seed germination.