Abstract: The paper aims to find out the cause of green spot disease of jujube. Through inoculating pathogen, Analysis distribution of disease fruit, gush medicine and fertilize. The causes of green spot disease occurring on jujube fruit were studied. The factors related to fruit location in different parts of tree crown, different green spots on the same fruit, and the calcium content of fruits were investigated. The results showed that fruits in the middle of tree crown had higher incidence rates (22.23%) than in other parts (give % here). Green spots in same fruit, the shade sides and middle parts had higher incidence rate at 51.73% and 41.38% respectively. The green spot organism was cultured, purified and then inoculated onto healthy fruit. The result showed that the inoculated fruit was not been infected, suggesting that green spot was not caused by fungi. The calcium content of diseases fruit was significantly lower than the health fruit. Therefore, green spots disease might be caused by the low level of calcium or deficiency of other minor element.