Abstract: To understand the translocation and distribution regularity of photosynthates in cotton leaves under drought stress, an experiment was performed under a water proof canopy with different levels of soil moisture. The translocation and distribution of 14CO2 photosynthates on low part “boll–leaf system” were studied by feeding 14CO2 to low main stem leaf at full–bud and florescence stages. The results showed that，with the increasing level of water deficit, the quantity of detained 14C–photosynthates in the mark leaf were increased while the export were decreased；14C–photosynthates in immature boll and roots increased but they declined in the mature boll and the growing point of main stem. In addition, the results of the fiber quality showed that suitable water stress did not have a remarkable influence on the fiber quality at early growing stages of cotton.