Data communication method and system, data transmitting/receiving device

The invention provides a data communication method for user equipment in the state of CELL_FACH, comprising the following steps that: a radio network controller sends data of the user equipment to a node B; when a specified event happens in the user equipment, the radio network controller sends a notification message to the node B; the node B does the corresponding treatment to respond to the notification message. The invention also provides a data communication system for the user equipment in the state of CELL_FACH and a data sending device as well as a data receiving device. The technical proposal of the invention has the advantages of saving the radio channel resources and decreasing the transmission delay, thereby reducing the transmission packet losing rate.