Urbanization is main driving force to the urban agriculture development and its structural transformation within metropolitan. To explore the conversion characteristics of the urban agricultural structure has a great significance in optimizing the relation of urban function and urban agriculture and their sustainable development in the process of rapid urbanization. Based on the indicators of agro-structure, agro-structure coefficient and agro-structure conversion direction coefficient, we analyzed the spatial-temporal conversion of agricultural structure in Xi'an metropolitan zone during 1999-2013. These results were as follows: ①Rapid urbanization resulted in huge changes of proportion in urban agriculture with the gradual decrease of grain crops production and the great increase of vegetables and fruits production and agro-recreation services in Xi'an metropolitan zone. A significant conversion occurred from traditional agriculture to urban modern agriculture, which showed that there were more intensive, fresh and ecological production, larger proportional agro-recreation services and high-tech facility's inputs. ②From 1999 to 2006, the rapid improvement of urbanization from low to higher level greatly promoted the urban agricultural structure adjustment and shift to modern agriculture in Xi'an metropolitan zone; Thereafter as the demand structure for agricultural products and services from citizen was constantly stable, the change ratio of agricultural structure gently dropped; ③With the enhancement of urbanization level and the reduction of urban agro-structure coefficient, the hierarchy level of urban agricultural structure gradually evolved into higher stages, and there was higher hierarchy level in urban area than in urban fringe and suburban area in space; ④The indicators of agro-structure conversion direction coefficient on grain crop in each district and county of Xi'an metropolitan zone all were less than 1, which showed that the transformation from planting to vegetables, fruit and the cultural leisure industry was more outstandingly. Agriculture was changing towards modern agriculture in metropolitan.