To study the impact of meteorological moisture parameters on sugarcane stem elongation, the sugarcane data and the corresponding meteorological moisture parameter data from the agrometeorological experiment station of Liuzhou from 2003 to 2007 are used to conduct statistical regression analyses by SPSS. The results show that the 10day sugarcane elongation has significant positive correlation with 10day water income amount, as well as 10day precipitation, water surplus and deficit, and evapotranspiration from 2003 to 2007; the results of the 5year data analysis show the same relation. The water income amount in the current 10day period has closer relation with the sugarcane elongation than that in the previous 10day period, and i. e., that in the first previous 10day period has closer relation with the sugarcane elongation than that in the second previous 10day period, and so on. It is concluded that water income amount is the key climatic factor for sugarcane elongation, and water income amount has an lagging and accumulative impact on sugarcane elongation.