In order to explore the feasibility of planting sweet sorghum in sugarcane growing area to prolong milling duration for bioethanol production, 15 varieties were sown monthly from March to September in Liuzhou of Central Guangxi Zhuang Autonomous Region. Yields of fresh stem, grain and leave were documented. The results showed that all varieties grew well when sown from March to August, but could not get mature when sown after late September. The high fresh stem yields were observed for the varieties Sart and PT3-S, 79.28 t/hm2 and 78.58 t/hm2 for single growing season, and 157.95 t/hm2 and 155.25 t/hm2 for two growing seasons. Ripening began from the end of June to late December, making the feed stock available for ethanol production from July to the end of December, even January next year.