Abstract: The content change of dry matter, starch and reducing sugar and their mutual relationship of 5 breeds of potatoes in the storage period was analyzed and researched in this experiment. Result indicated that the content of dry matter showed extremely significant difference between the tubers of different breeds of potatoes in the storage period (P<0.01); the content of dry matter in the tubers of the same breed of potato showed no significant difference between different storage period; the content of starch and reducing sugar showed extremely significant difference between the tubers of different breeds of potatoes and between different the storage period (P<0.01). There was significant positive correlation between the content of dry matter and the content of starch in the tubers in the storage period (r=0.902).