- Water is a vitally fundamental element for the chemical and biochemical processes supporting plant metabolism. However, some areas face the problem about water management, resulting in drought stress to plant. Drought is one kind of environmental stresses that can cause greatly reductions in yield. However, plants don’t need a lot of water all the time. This study aimed to investigate the effect of water stress during sugarcane development on sucrose yield in order to gain the knowledge to find the good management for sugarcane growers. Moreover, It has been reported that water stress affects sugar accumulation in some plants. The objective of this study is to examine the effect of water stress on sucrose accumulation and physiological and molecular changes in sugarcane in order to determine what stage of sugarcane development can be induced by water stress to increase sugar accumulation to higher level. In this study, 7 month-sugarcane and 10 month-sugarcane were treated with water stress. The level of water stress were divided into 4 groups ; control, 10 days no watering, 20 days no watering and 30 days no watering. At harvesting time, the physiological changes (such as the height, the number of internodes and the weight) and the values related with the sweetness of sugarcane (such as Brix, Pol and CCS) of each treatment were measured. The height and the weight of sugarcane of each treatment didn’t differ significantly. But sugarcanes which were treated with 30 days no watering at 7 month-age have the smallest number of internodes, 14.33 internodes/plant, while the control plants have 21 internodes/plant. The value of Brix, Pol and CCS were affected by water stress. The lowest value of Brix , 10.14, was found in treatment with no watering 10 days at 7 month-age. While treatment with no watering 20 days at 7 month-age has the lowest value of Pol and CCS, 8.50 and 6.30 respectively. However, sugarcanes which were treated with water stress at 10 month old for 30 days showed similar value for Brix, Pol and CCS as those of control. This result suggested that we can reduce water use prior harvest for sugarcane without any effect on sugar yield. Morever, the expression of Sucrose phosphate synthase (SPS) and cell wall invertase (CWI) were investigated. SPS and CWI were induced by water stress prior harvest. This suggested that SPS and CWI might involve in sugar accumulation in sugarcane.