西瓜果实糖分的积累类型是“中间类型”。其光合产物是棉籽糖和水苏糖，并以此形式运输，但是最终进入果实的糖分仍然是蔗糖。因此，蔗糖是许多果实中糖积累的主要形式，是果实品质形成的重要因子。在西瓜果实糖分积累的过程中，蔗糖转化酶、蔗糖磷酸合酶、蔗糖合酶是三种最为重要的代谢酶。同时，它们控制着另外两种糖分:果糖、葡萄糖的合成与转化。使得西瓜果实在成熟时各种糖分的积累达到蔗糖、果糖、葡萄糖含量平衡，产生西瓜特有的风味。

The type of sugar accumulation of Watermelon fruit is "intermediate type".Their photosynthetic production are raffinose and stachyose, and by this form to transport.But finally the sugar into the fruit is sucrose yet. Therefore, sucrose is the main form of sugar accumulation and the important factor of fruit quality in many kind of fruit. During the process of sugar accumulation of watermelon fruit, the sucrose invertase, sucrose phosphate synthase and sucrose synthase are the most important metabolic enzymes. At the same time, fructose and glucose are controlled by these enzymes. So, these enzymes make the three kinds of sugar that sucrose, fructose and glucose become balance at the time of watermelon fruit maturity.